Evaluation of Existing and New Periodic Tables of the Elements for the

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Evaluation of Existing and New Periodic Tables of the Elements for the Chemistry Education of Blind Students Dennis Fantin,*,† Marc Sutton,‡ Lena J. Daumann,§ and Kael F. Fischer∥ †

Department of Chemistry and Biochemistry, California Polytechnic State University, San Luis Obispo, California 93407, United States ‡ Center for Accessible Technology, Berkeley, California 94703, United States § Department of Chemistry, University of California, Berkeley, California 94720-1460, United States ∥ Department of Pathology, University of Utah School of Medicine, Salt Lake City, Utah 84132, United States S Supporting Information *

ABSTRACT: As a symbol of the power and majesty of science, the periodic table has inspired many scientists-to-be to investigate the deep secrets of nature through the study of chemistry. In the spirit of inclusion, blind students too deserve and need to have their curiosity about the inner workings of nature stimulated through greater exposure to this symbol and tool of science. To this end, the authors have designed two accessible electronic periodic tables that are available for immediate download without charge: One version, the Cal Poly DAISY Periodic Table (CP-DPT), is in the DAISY format and is designed to be used on digital audio devices and electronic Braille note takers; the other version, the Cal Poly Excel Periodic Table (CP-EPT), is an Excel workbook and is accessed with a screen reader-equipped personal computer. Both versions contain data and descriptive information about the elements. We believe that distribution of these tables will aid the dissemination of chemical knowledge, and support STEM education for blind students. This report also evaluates periodic tables presented in Braille and audio-tactile formats. In addition, periodic tables available on the Web are evaluated in relation to screen reader access. HTML tables created according to standard Web content accessibility guidelines can be entirely accessible, whereas PDF and FLASH formatted tables were found to be largely inaccessible. Hence, HTML is the preferred format for accessible tables. KEYWORDS: Computer-Based Learning, Internet/Web-Based Learning, Minorities in Chemistry, Atomic Properties/Structure, General Public

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INTRODUCTION Recently, progress has been made in several areas aimed at making chemistry education accessible to blind and visually impaired students.1−8 This is most dramatic for low vision students for whom the development of video magnification systems promises to make the entire university chemistry curriculum accessible with few limitations.5 Such devices consist of a small video camera on the end of an articulated arm connected to a computer monitor, and are used for close-up or distance viewing. With one such apparatus, a student is able to assemble glassware, view the meniscus, read dials and gauges, even see the writing on a chalk board, in fact, perform nearly all of the tasks demanded of a chemistry student both in and out of the laboratory. For blind students, laboratory course curricula have also been made more accessible with techniques that enable the student to carry out basic operations such as pouring, weighing, and transferring of chemicals.3 Furthermore, © 2016 American Chemical Society and Division of Chemical Education, Inc.

data acquisition systems using electronic sensors connected to a computer are becoming more common, and at least one such system has been modified to provide speech output.8 Admittedly, monitoring chemical changes as they occur continues to be a difficult challenge, but even here some progress has been made, notably the development of a submersible probe emitting an audible tone in real time that changes in response to the turbidity of the solution.2 Threedimentional representations of molecules and solids that can be visualized on a flat computer screen can also now be converted into tactile forms using 3-D printing, molecular modeling kits, and Braille-labeled tactile drawings.4,7 These tools have been used along with other interesting innovations, such as a Received: August 2, 2015 Revised: January 15, 2016 Published: February 22, 2016 1039

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11.5 in. Given the scarcity of Braille textbooks, it follows that there is also a scarcity of Braille periodic tables.

technique to depict IR spectra of molecules using nonspeech sounds, to complement organic and theoretical chemistry courses.6 The foregoing is a brief introduction to the subject of chemical education for blind and visually impaired students. Without ready access to the periodic table of elements (PTE) however, the blind student will lack what all other students take for granted. The PTE is therefore the focus of the current report. The PTE is without parallel as a teaching tool. In one elegant display, it shows us all of nature’s building blocks, and provides a basis to explain both chemical bonding and atomic structure. As a visual symbol, the periodic table stirs the imagination, and announces the power and mystery of science. Its oversized, often grand display in the chemistry lecture hall functions not only as a useful educational aid, but also as an emphatic reminder that science is at the core of learning; thus, it serves as both a visceral symbol of modern science and a practical support to promote its investigation. “I had an overwhelming sense of Truth and Beauty when I saw the Periodic Table, a sense that this was not a mere human construct, arbitrary, but an actual vision of the eternal cosmic order, and that any f uture discoveries and advances, whatever they might add, would only reinforce, reaf f irm, the truth of its order.” Oliver Sacks9 Many other young scientists-to-be have been similarly impelled to look deeply into nature’s secrets upon first seeing and learning about the periodic table. The list includes Nobelists Sidney Altman and Joseph Murray, physicist Freeman Dyson, mathematician Jacob Bronowski, and even the novelist and physicist C. P. Snow.10−14 Among blind people, who also have an inherent right to explore the nature of the physical world, and who share with other members of society the need to be inspired by symbols, the basic shape and organization of the periodic table may be unknown. While a blind student might find out about the PTE in a book, or when a friend or teacher alludes to its presence as a printed chart on the wall, the ongoing experience of a sighted person encountering the PTE repeatedly in the classroom can, for a blind person, be matched only by exploring tactile (including Braille) or auditory versions of the table. This report evaluates the accessibility of PTEs that appear in Braille and audio-formatted chemistry textbooks, in some commercially available products, and mainstream chemistry Web sites. The two novel digital versions of the PTE developed at California Polytechnic State University are presented. These are the Cal Poly DAISY Periodic Table (CPDPT) and the Cal Poly Excel Periodic Table (CP-EPT). They have been tested by the authors and are freely available for download.15 These accessible PTEs are intended to be used as part of the educational infrastructure in support of blind students who enroll in chemistry or other STEM (Science Technology Engineering and Mathematics) courses at the high school or university level.

PTEs in Audio-Formatted Textbooks

Learning Ally, formerly Recordings for the Blind and Dyslexic, a lending library with over 70,000 titles, is the principle source of digital audio textbooks for blind students in the United States.20−22 Learning Ally books are read in their entirety by trained volunteers; tables, graphs, and captions are read along with verbal descriptions of all illustrations. Of the hundreds of chemistry textbooks that are available in audio-format, most feature a PTE and extensive tables of element properties. And while these tables are read aloud line-by-line, insufficient indexing of the digital audio files makes navigating by row and column an arduous process that restricts learning. There is therefore a need to supplement the spoken word recordings and Braille representations of the PTE and data tables of element properties with other approaches for acquiring tabular information. PTE Products for Blind Learners

The American Printing House for the Blind (APH) has developed a simple Braille version of the PTE, the “Periodic Table of the Elements Reference Chart and Booklet”, which, like the typical PTEs in Braille textbooks, extends across two Braille pages.23 In this version of the PTE, raised lines enclose the element squares which contain the element symbols and atomic numbers (Figure 1). One weakness of the APH PTE is

Figure 1. PTE in Braille of the American Printing House for the Blind. Picture taken from APH Instructional Products Catalog & Parts Catalog and reprinted with permission of APH.

PTEs in Braille-Formatted Textbooks

According to the Braille catalog of the American Printing House for the Blind (APH), the authoritative source for books available in Braille and audio formats,16 since the year 1999, only one university general chemistry textbook and one organic chemistry text have been transcribed into Braille in their entirety.17,18 To date, no physical chemistry or biochemistry textbooks have been transcribed into Braille in their entirety.19 In the few chemistry texts that do exist in Braille, the PTE is normally arrayed across two Braille sheets, measuring 22 in. ×

that the raised lines enclosing the elements are somewhat indistinct. This tends to slow tactual navigation, impeding the ability of the reader to form the desired gestalt impression of the PTE that a nonvisually impaired person tends to gain from seeing a printed version of the table. In general, stronger raised lines allow for more rapid scanning, which translates into a more defined cognitive image. Touch Graphics, Inc. has designed the first commercially available product that contains both a tactile periodic table and 1040

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Figure 2. Periodic Table for Talking Tactile Pen. Reprinted with permission from Touch Graphics, Inc. and Smith-Kettlewell Eye Research Institute.

Figure 3. LabQuest instrument and periodic table screenshot. Reprinted with permission from Vernier Software & Technology.

(Figure 3).8 This hand-held device is primarily used to collect sensor data for pH, temperature, mass, etc. It is an example of a new class of laboratory instruments built according to principles of Universal Design, defined as “the design of products and environments to be usable by all people, to the greatest extent possible, without the need for adaptation or specialized design”.26 The SciVoice talking LabQuest’s PTE is navigated using four raised arrow keys, and a center key that is used to scroll through a list of 20 element properties. If all the data pertaining to a particular element are of interest, the student first navigates to that element with the arrow keys, and then taps the center key until each of the items in the data list is spoken. Alternatively, as with the Touch Graphics PTE, if the task is to investigate how a particular property, such as melting point, changes as a function of position, the student begins by tapping the center key until the melting point property is spoken. Pressing a lock button fixes the entire display on that property. A recent report introduces an audio PTE system in which the student uses a smart phone to interact with a wall poster displaying the periodic table (Figure 4).27 In this Quick Response coded Audio Periodic Table of the Elements (QRAPTE), each element on the printed poster is tagged with a unique quick response bar code (QR code) which links to a

an electronic interface to additional information about the elements.24,25 The periodic table is used with a pen-based audio-tactile reading device. The PTE is embossed on a 17 in. × 11 in. vinyl sheet with the element symbols enclosed by raised lines (Figure 2). The pen contains a small camera near the tip that images and interprets dot patterns preprinted onto the sheet. These dot patterns are located in the same area as the Braille dots that represent the letters and numbers on the PTE. The user explores the table with one hand and with the other hand taps the pen on the element of interest. When a tagged region is engaged requiring a scratching motion with the pen tip (which some users find difficult to master), the pen speaks the relevant information aloud using synthetic speech. If the properties pertaining to a single element are of interest, the pen can be tapped repeatedly on the element square. Each time the pen is tapped, it speaks the data in one of 16 available categories (atomic mass, radii, etc.). Alternately, the speechdisplay can be locked on a particular property and the values of that property for the elements can be more conveniently compared. Another commercial product that includes a PTE, as one of its functions, is the Sci-Voice Talking LabQuest, which is a blind-accessible interface device that is used as a data acquisition system for chemistry and physics laboratories 1041

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COMPUTER BASED PTEs

PTEs on the Web

There are many representations of the PTE, as well as collections of chemical element properties and narrative descriptions of the elements. The record is mixed concerning the accessibility of this material. In this section, we will consider and compare the accessibility of PTEs available to students using a screen reader equipped computer. As HTML is the primary markup language for creating Web pages, we begin with an evaluation of HTML-coded PTEs from five professional Web sites, followed by analysis of a PTE created by the authors in the Microsoft Excel file format. The section concludes with an evaluation of PTEs represented in the PDF file format and those rendered using the Adobe Flash web browser plugin. To access the periodic table from a computer, either locally or through the Internet, the blind student needs a computer equipped with a text-to-speech software application known as a screen reader.29−31 The screen reader uses synthetic speech to speak the contents of the computer display in response to keyboard commands that are used to navigate and control features of the file. On a Web page for example, the user can move rapidly back and forth through the text using screen reader commands, and this gives a sense for how the page is laid out. Comprehension is increased when there are navigation elements such as headings, lists, form fields, combo boxes, and data tables present, all of which the screen reader should be able to identify.32,33 Like other navigation elements, when a data table such as a PTE is present in an HTML-coded Web page, it can be accessed and navigated using specific key stroke commands. For example, when the letter T is pressed in JAWS for Windows, a popular Windows-based screen reader, the user might hear “Table with 18 columns and nine rows”.29 The arrow keys and various key combinations are then used to navigate through the table, and when the navigation pointer passes over a cell, its contents are spoken aloud.

Figure 4. Quick Response coded Audio Periodic Table of the Elements.27 Reprinted with permission from ref 27. Copyright 2012 American Chemical Society.

video description of the element from the “Chemistry In Its Element”, Royal Chemistry Society (RCS) Web site.28 Using the phone’s view finder, the student navigates to the element of interest, and clicks on the QR code which activates a YouTube video in which an RCS laboratory chemist gives a learned, several minutes long description of the element and its properties. The authors of the QR-APTE report state that learning through listening is not only preferable to Braille learning but is more powerful specifically because it “avoids Braille reading”. This is a controversial statement that fails to account for the fact that many blind people use Braille as an ordinary part of life. Ultimately, the authors of the report decide to add Braille labels to the PTE posters “for untutored learning of blind and visually impaired students.” Unlike the commercial Touch Graphics and LabQuest PTEs, the QR-APTE does not provide a way to explore the table while locked on a single element property. These PTE products differ considerably in hardware, platform design, and presentation. As a result of these dissimilarities, we chose to outline the features of each PTE but not attempt to make quantitative comparisons of their accessibility. The DAISY Periodic Table, CP-DPT, described below, has its own unique features and is likewise not evaluated quantitatively.

PTE Evaluation Criteria and Methodology

Table 1 contains Web-based PTEs in HTML, PDF and FLASH, as well as in the Excel format. Each PTE was given a numerical score of 1 (inaccessible) to 4 (fully accessible) in four different categories, reflecting the performance of the PTE using the screen reader interface and summary Overall Accessibility score: the arithmetic mean of the other categories.

Table 1. Comparison of Computer Based Periodic Tables’ Screen Reader Accessibility Accessibility Scoresa Resource Name

Format

PTE Geometry

Contextual Element Data

Basic Element Data

Extended Element Data

Overall Accessibilityb

Chemicool Webelements Los Alamos It’s Elemental Photographic CP-EPT IUPAC NIST ACS Interactive

HTML: Web site HTML: Web site HTML: Web site HTML: Web site HTML: Web site Excel: Downloadable PDF: Downloadable PDF: Downloadable FLASH: Web site

3 3 4 3 3 4 1 1 1

1 1 1 1 1 4 1 1 1

4 1 4 3 4 4 1 1 1

4 1 2 2 4 4 1 1 1

3.0 1.5 2.8 2.3 3.0 4.0 1.0 1.0 1.0

a For 9 computer based PTEs, four aspects of PTE accessibility, via screen reader, are systematically scored as follows: 1, inaccessible; 2, accessible with many limitations; 3, accessible with few limitations; 4, accessible. Definitions of the four score columns, PTE geometry and the Element Data categories, are given in the text (PTE Evaluation Criteria and Methodology). bOverall Accessibility is reported as the mean of the scores.

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number of empty cells varies, which may be especially confusing to the beginning student. The Los Alamos PTE does not provide access to contextual element data. The basic element data are available via the screen reader but in two steps. When linking to an element from the main table, a list of elements ordered by atomic number appears. Pressing on the element from this list brings up another small table containing data on six properties, as well as narrative descriptions of history, uses, compounds, sources, handling, and isotopes. The Los Alamos site falls short in that it does not include tabulated data covering extended element properties, which is a feature of some of the other Web-based PTEs. The Los Alamos site has a combined score of 2.8. Like most of the other PTEs, The Chemicool Periodic Table has the common problem of inaccurate geometry presentation, and it does not provide contextual element data.36 It does however provide good access to basic and extended element data as follows. When an element is accessed from the main table, a page is brought up containing a table with data on 12 properties. The page also contains narrative descriptions of discovery, appearance, and characteristics; uses; and abundance and isotopes. This Web site is coded with HTML table and heading markers that afford simple and complete access to the contents. The Chemicool PTE has an Overall Accessibility score of 3.0. Like most of the other HTML PTEs, The Photographic PTE gives an inaccurate impression of the geometry of the table in the first three periods.37 Also, like all the other HTML PTEs reviewed, it does not provide contextual element data. It does however provide access to basic element data and to a very impressive array of extended element data. When an element is accessed from the main table, a further small table is brought up containing three element properties and a cell labeled “Full Technical Data”, which, when linked to, brings up a page with three navigable tables with data covering an additional 106 properties. Accessing any one of these properties displays the elemental property data with the elements organized in one of three ways: in alphabetical order, by ascending atomic number, or by ascending property value. A unique feature of the Photographic PTE Web site is that it has a mostly accessible, long-form, 32 columns wide PTE on the second and subsequent pages of the Web site.43,44 The Photographic PTE’s hallmark is many pictorial representations of elements; however, these lack textual descriptions that would make them useful to screen reader users. The Photographic PTE has an Overall Accessibility score of 3.0. The “It’s Elemental PTE” inaccurately represents the PTE geometry.38 It also lacks access to contextual data. The basic element properties are provided but hard to find, being placed below an essay about the element in a section entitled Element at a glance. The Web site does not contain HTML heading markers which the screen reader normally depends on to move between sections of the Web page. The “It’s Elemental PTE” site fails to present tabulated extended element data, but there is an essay about each element by a research scientist with in depth knowledge of the element and its properties. The “It’s Elemental PTE” has an Overall Accessibility score of 2.3. The Webelements PTE, like most of the HTML PTEs, inaccurately represents the geometry of the first three periods.39 It also fails to convey contextual element data. Unlike all the other HTML PTEs, however, even the basic element properties are inaccessible using the screen reader, as are the extended properties. Webelements has been continuously curated by an

Note that other scoring systems exist in the literature to rate the accessibility of computer based tools for blind learners.34 The first category is PTE Geometry and reflects how successfully the Web site conveys the shape of the PTE through the screen reader interface. Note here that all of the PTEs are presented in the 18 column wide, medium-long form layout with the lanthanides and actinides set below the main table. The access to Contextual Element Data category measures the ease with which the data for individual element properties can be viewed in context with the rows (periods) and columns (groups) of the PTE. This is especially useful for illustrating the familiar patterns of element property variation when these properties are projected onto the Periodic Table’s structure, i.e., atomic radius generally increases when navigating through the elements from right to left or from top to bottom. Access to Basic Element Data reflects the ease with which element name, element symbol, atomic number, and atomic mass can be retrieved. The Extended Element Data reflects screen reader access to element properties beyond those considered most basic, and/or the presence of further narrative descriptions of the elements. Blind authors M.S. and D.F. reviewed and evaluated the computer-based PTEs using JAWS for Windows release 15.0.11024. The following HTML-based Web sites were reviewed. All contain periodic tables and additional information about the elements: “Online Periodic Table”, Los Alamos National Laboratory;35 Chemicool.com’s “Periodic Table and Chemistry” (Chemicool), Dug Stuart, MIT;36 “The Photographic Periodic Table of the Elements” (Photographic PTE), Theodore Gray;37 “It’s Elemental - The Periodic Table of Elements” (It’s Elemental), American Chemical Society;38 “Periodic Table of the Elements by WebElements” (Webelements), Marc Winter, the University of Sheffield.39 The “Cal Poly Excel Periodic Table” in the Excel file format (CP-EPT) is reviewed next,15 followed by two downloadable PTEs in the PDF format, and a Web site with a Flash PTE. The PDF PTEs are from the International Union of Pure and Applied Chemistry (IUPAC PTE),40 and the National Institute of Standards and Testing (NIST PTE).41 The FLASH PTE reviewed is the ACS Interactive Periodic Table (Interactive PTE).42 Only a single Flash Web site was included because of fundamental problems accessing Flash content with current screen readers. These nine PTEs were systematically analyzed for accessibility using the JAWS screen reader in conjunction with standards for presenting accessible tabular information as outlined in the Web Accessibility Initiative’s (WAI) Web Content Accessibility guidelines (WCAG 2.0).32 The WAI, which is a part of the World Wide Web Consortium, develops strategies, guidelines, and resources to help make the Web accessible to people with disabilities.33 Results are summarized in Table 1. HTML Formatted PTEs

Among all the Web-available PTEs reviewed, only the Los Alamos PTE correctly conveys the shape of the periodic table.35 This is because the screen reader speaks the word blank each time the cell pointer passes over an empty cell. For example, when navigating across the first row of the table, the listener hears “1 H 1.008” followed by the word “blank” 16 times before helium is encountered. This contrasts with all the other HTML PTEs in which the word blank is spoken only once when arrowing across any of the first three periods, even though the 1043

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Figure 5. Organization of the Cal Poly DAISY Periodic Table. The five sections of the CP-DPT are represented with their corresponding page numbers in shaded boxes. The organization element property values within the pages and list elements of sections one, two, and three are shown in tables below the respective sections. DAISY pages are represented as rows and data set elements in the lists contained on each page are represented as columns. When navigating to a list position on a page, the contents of the cell will be spoken by the DAISY reading device.

Excel Formatted Periodic Table

academic chemist since it appeared in 1993, and it contains a vast array of current research-level data and information about the elements from a variety of perspectives; unfortunately, these data are inaccessible to the screen reader. The Webelements PTE has an Overall Accessibility score of 1.5.

The CP-EPT correctly conveys the geometry of the PTE, a feature it shares with only the Los Alamos PTE.15 By design, it also provides element data in period and group contexts and easy access to both basic and extended element data. The CP1044

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EPT is a downloadable workbook,15 containing 27 2D Excel spreadsheets (see Supporting Information). The student navigates within and between the spreadsheets, using the arrow keys and other Excel-specific key stroke commands, which are accessible to the screen reader. The first sheet provides an introduction to the chemical elements and describes the modern periodic table. The second sheet lists the elements numerically in the first column, and presents 25 associated physical and chemical properties in the columns to the right of each element. The following 24 sheets (WK3WK26) each displays a single property, arranged in the shape of the standard PTE. Thus, the student has the choice either to look up the properties of an individual element, or investigate how a particular property changes when viewed in the standard representation of the PTE. The second approach is especially useful for illustrating periodic trends for individual properties such as atomic radius, electronegativity, and first ionization energy, first encountered in introductory chemistry courses. The final sheet WK27 lists the elements alphabetically by name and by atomic symbol with and without the atomic masses. The CP-EPT receives an overall score of 4.0, fully accessible.

blind. The HTML PTEs vary in terms of design and screen reader access.

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TWO NEW ACCESSABLE PTE REPRESENTATIONS Here we present two tested and freely downloadable versions of the PTE; the first is intended for portable digital audio players, and electronic Braille note takers.15 The second is designed to be used on a computer using audio screen reading software. Cal Poly DAISY Periodic Table

The CP-DPT introduces the PTE with a series of accompanying lists and data tables pertaining to the elements.15 It can be used to investigate properties of the elements and also serves as a quick reference guide in situations where the student does not have a computer. This version is in the DAISY (Digital Accessible Information System) format, and is primarily designed to be used with a digital audio player.50 Such portable audio devices have largely replaced cassette and CD players, and can handle multiple file types including audio (human speech) and text (synthetic speech) formats. The CPDPT uses synthetic speech. It is also noteworthy that the CPDPT is compatible with electronic Braille notetakers. The CPDPT is available for free download15 and has also been included in the Supporting Information. A limitation of the DAISY software is that it does not support navigation in two dimensions. Given this limitation, it is not possible to navigate through the CP-DPT in both the vertical and horizontal directions. It is possible, however, to navigate forward and back through a 1D data list; accordingly, the DAISY PTE is designed to track the elements in order of atomic number from hydrogen to element 118. It also divides the PTE, and all of the data connected with the properties of the elements, into individual rows and columns. In all, the file is divided into 795 1D data lists. Because of the structure, size, and complexity of the CP-DPT, extensive use is made of page, line, and user-defined level indexing to aid navigation. The CPDPT consists of an introduction and four other parts (Figure 5). The introduction, pages I to XI contains a description of the properties of atoms and elements, followed by an overview of the modern PTE. The element data are then organized and presented in different ways: first, by atomic number from element 1 to 118, with and without atomic masses; then by individual period and group, again with and without atomic masses. Part One, pages 1−118, presents the elements in order of atomic number where the page number corresponds to the atomic number. Each page displays one list corresponding to one element’s name and 25 associated physical or chemical properties. This section is useful as a quick reference guide. Part Two, pages 200−225, associates the individual element properties, one property per page, with the periods (rows) of the PTE. For example, on page 205 which is the page associated with boiling point, there is a list of nine data sets. Each list element contains the names and boiling points of elements of one of the seven periods, followed by the lanthanides and actinides. Part Three, pages 300−325, is analogous to Part Two, except that each page contains lists corresponding to the PTE groups 1−18. Again, each page displays a single property, and each list element on a page contains a data set according to group. Parts 2 and 3 can be used to investigate how individual element properties change across each of the periods and groups of the PTE, a subject matter covered in all introductory chemistry courses. Part Four,

PDF Formatted PTEs

Many PDF-formatted PTEs available on the Web are partly or completely encoded as images and are inaccessible to screen readers. It is possible to mark up or tag a PDF file creating an interface similar to accessible HTML, but support for tagging of data tables is still rudimentary and a search of the Internet produced no examples of accessible PDF-formatted PTEs.45−47 The IUPAC and NIST PTEs are examples of image-based PDFs which are inaccessible to screen readers.40,41 They each receive an overall score of 1.0, inaccessible, when judged according to the same criteria as the other computer-based PTEs. Flash PTEs

It is also generally understood that in the interest of access, Adobe’s Flash browser plug-in should be avoided for presentation of tabular data. The reason is that while screen readers have come a long way in their ability to provide accessible text and navigation to the blind user, certain programmatic elements such as embedded Flash content remain largely beyond the scope of current technology. Although some minor Flash elements can be made accessible, tables of data cannot be.48,49 The Interactive PTE is an example of an inaccessible Flash-coded table.42 Like the PDF PTEs, it merits an overall score of 1.0, being fully inaccessible. Summary of Computer-Based PTEs

The Overall Accessibility category (Table 1) represents the arithmetic mean of the scores that make up the accessibility assessment. The Cal Poly CP-EPT, designed with screen reader access in mind, scores highest with an overall score of 4.0. Among the HTML PTEs, the scores are Chemicool PTE, 3.0; Photographic PTE, 3.0; Los Alamos PTE, 2.8; It’s Elemental PTE, 2.3; Webelements PTE, 1.5. The PDF and Flash PTEs were rated as inaccessible with scores of 1.0. As the most extensive testing was done with one particular screen reader, JAWS for Windows, the ranking represents a considered but not all-inclusive measure of overall screen reader accessibility. The conclusion that the CP-EPT table is the most, and PDF and Flash PTEs the least accessible seems clear, and is unsurprising since the lead author of the CP-EPT is himself 1045

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the simplicity of the CP-EPT, when navigating within a spreadsheet, the audio response is so fast that it can lead to the formation of an overall mental image of the PTE. For example, when using the right and left arrow keys to scan the third row of the table, one starts at the left with Sodium, and then taps once to the right to Magnesium. Subsequent right arrow keypresses causes the word “blank” to be spoken 10 times before aluminum is reached. Testing reveals that, with each key-press, the contents of each cell are spoken with no perceived delay. Because the chart is geometrically rather simple, the speed and responsiveness of the audio-tactile scanning process begins to reveal the organization of the chart even though the blind student is unable to see it. The authors find that this experience approaches the effect of tactually exploring a physical PTE with the element blocks raised to a considerable height above the background, in which case navigation through the PTE can be rapid enough as to permit the formation of a strong mental image of the table. When the lead author, D.F., who is blind, took his first chemistry course, his father built such a tactile periodic table, made of wood, with element blocks raised above the background. This table could be easily and quickly reviewed tactually, which also revealed its organization. There are two further recommendations that if implemented the authors believe would foster the study of chemistry for blind students: (1) Dramatically expand the distribution of Braille and tabletop tactile PTEs, so that blind students will more routinely run across the periodic table in their classes; and (2) Develop large-scale tactile PTEs suitable for mounting on the walls of high school chemistry classrooms and science lecture halls. Such large format tactile PTEs combining print and Braille, and perhaps 4 ft high and 10 ft wide, could be used directly as instructional aids by a blind student or instructor. The presence of such tables would, through their sheer size, also communicate an air of importance, and could be used by blind and sighted people alike.

pages 400−404, contains alphabetical indices of the elements by element name and by element symbol, with and without the atomic mass. Development and Testing of CP-DPT

The DAISY consortium produces tools for developers of DAISY publications.50 The authors used the DAISY Consortium’s Microsoft Word Save As plug-in to mark up the data for use with DAISY playback software and hardware. The following digital audio devices were tested to confirm the accessibility of the material presented: Victor Reader Stream, Humanware USA;51 BookSense, and VoiceSense, HIMS, Inc.52 The DAISY standard was closely followed in evaluating these products, and no incompatibilities were found. The DAISY Version was also tested and found to be compatible with electronic Braille notetakers including the Braille Note, Humanware USA; and the Braille Sense, HIMS, Inc.51,52 Although the present report does not focus on the accessibility of smart phones and tablets, testing also revealed that the CPDPT is usable on the iPhone 5S under iOS 8.1, with the Read2Go app from BookShare; and with the Voice Dream Reader app Version 3.2.0.53,54 Development and Testing of Cal Poly Excel Periodic Table

As described above in Summary of Computer-Based PTEs, a Excel formatted CP-EPT is available for free download.15 Of the computer based PTEs tested, this PTE was the most accessible to screen reader users. Screen reader manufacturers have worked with Microsoft for many years to make their suite of Office software accessible to blind users. We used the popular and accessible Microsoft Excel 2010 application for the CP-EPT. The CP-EPT performs well with PC Excel versions 2003, 2007, and 2010. With respect to screen readers, the CPEPT has been tested and works well on PCs using the most common screen reading programs: JAWS for Windows, release 15.0.11024; WindowEyes, release 8.4; and NVDA Release 2014.4.29−31 The CP-EPT has also been tested and found to be satisfactory using VoiceOver with the Macintosh Operating System Version 10.9 (Mavericks); and with Amis Version 3.1.3, the free Windows screen reader.55,56

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CONCLUSION The PTE is the principle compendium chart for the physical sciences. Even more than the table of isotopes, its shape is immediately and universally known to all scientists, who depend on it to refresh their knowledge of atomic patterns, properties, and data. Only recently has this most powerful tool and symbol of science been made more accessible to blind students. We present here two new digital PTEs. The first is the Cal Poly DAISY Periodic Table (CP-DPT), in the DAISY format designed to be used on digital audio devices and electronic Braille note takers. The second is the Cal Poly Excel Periodic Table (CP-EPT), an Excel workbook which can be accessed with a screen reader-equipped personal computer. These downloadable PTEs are offered without charge. The authors believe that distribution of these tables will aid the dissemination of chemical knowledge, and support STEM education for blind students. In the interest of equal access, and considering the ubiquitous reach of the Internet, the authors recommend further that the developers of Web content structure their PTE displays bearing in mind the current state of screen reader technology. HTML-coded tables can be handled most easily by screen readers and can be marked-up to include links to other data tables and information. PDF and Flash-coded tables generated in visual mode are either not recognized by the

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DISCUSSION This report reveals many of the accessibility barriers encountered in most chemistry Web sites from the standpoint of screen reader access. It is true, however, that online information about the elements can be acquired even by relatively inexperienced blind computer users by using a search engine. Typing words or a query in the browser’s search box: second ionization energy of tungsten; allotropes of titanium, usually retrieves a correct response in one of the first few search results, and often without the need to open the link. Still, care must be taken to retrieve such data from professional chemistry Web sites as noted by Izci et al.57 The organization of the PTE, the powerful concept inherent in the PTE groups, and the relative placement of the s- and p-blocks are not as easily conveyed using a search engine. Among the computer-based PTEs evaluated, only the CP-EPT and the Los Alamos Web site offer unambiguous renderings of the table’s spatial layout, meaning that each cell in the table is spoken, even when the contents of the cell are empty. The CP-EPT alone conveys contextual element data suitable for exploring period and groupwise trends. One result that has emerged from these tests deserves particular mention. Due to the speed of modern computers and 1046

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screen reader or are not read correctly. Therefore, image-only display modes should be avoided.

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available on the ACS Publications website at DOI: 10.1021/acs.jchemed.5b00636.

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Cal Poly DAISY Periodic Table (CP-DPT) (ZIP) Cal Poly Excel Periodic Table (CP-EPT) (XLS)

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS

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REFERENCES

The authors wish to thank Kristina Pfeiffer, Neely Atamaniuk and Emily Hannigen for assistance in the preparation of the CP-DPT. Thanks also to Profs. Julie Hollien and Robert Metts for critical reading of the manuscript and helpful suggestions. L.J.D. gratefully acknowledges a Feodor-Lynen scholarship of the Humboldt foundation.

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NOTE ADDED AFTER ASAP PUBLICATION An uncorrected version of this paper was inadvertantly published on February 22, 2016. The corrected version was published on February 23, 2016.

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DOI: 10.1021/acs.jchemed.5b00636 J. Chem. Educ. 2016, 93, 1039−1048