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In the Classroom

Engaging Students in Early Exploration of Nanoscience Topics Using Hands-On Activities and Scanning Tunneling Microscopy Ping Y. Furlan Department of Chemistry, University of Pittsburgh at Titusville, Titusville, PA 16354; [email protected]

Nanoscience is the study of materials and their behavior at particle sizes measured in nanometers. At this small size, surface and quantum phenomena are prominent. Consequently, materials behave in an unconventional way and exhibit new and size-dependent properties. Because new properties allow for novel applications, this makes nanoscale materials extremely interesting. This modern field, having advanced at a remarkably fast pace ever since the invention of the scanning tunneling microscope (STM) in 1981, holds much promise and has the potential to affect every aspect of our daily lives. Early education in nanoscience will enhance students’ academic and occupational advancement opportunities (1, 2). We report here our experiences introducing first- and second-year students to nanoscience at a two-year regional campus (~500 students, many of whom are underserved as either rural, economically disadvantaged, or minority students) by utilizing a set of strategies emphasizing a hands-on approach. Strategies and Pedagogical Principles Using Nano To Improve Student Attitudes Students’ attitudes toward chemistry play an important role in their learning. Pintrich’s research (3) suggested that positive attitudes relate positively to self-regulated learning: students who believe their course work is interesting, important, and useful are willing to put forth more effort and spend more time engaged in their school work. Higher performance on science assessments has been shown to correlate with positive student attitudes toward science (4, 5), suggesting that interest leads to a deeper level of learning (6). As a science field with great potential for advancing knowledge and creating new applications, nano activities will likely be viewed by students as relevant, important, and useful (helping career or life in general); thus, serving as an ideal strategy to improve students’ attitudes toward chemistry, enhance their learning, and better prepare them for future scientific challenges. Employing an Underlying Instructional Theme The underlying instructional theme is centered on answering questions that include: “What makes nanomaterials unique?” “How can they be made and characterized?” “How can they be used?” Activities (7–14) are selected and tailored to illustrate this theme, reflect the course objectives, and meet and increase students’ skill level. Emphasizing Breadth The theme leads to a breadth-first approach, touching upon important areas of nanoscience, providing students basic nanoscience concepts and skills, and increasing their awareness of the exciting possibilities of this emerging field. This includes the uniqueness of nanomaterials, nanosynthesis and nanofabrication, nanoscience instrumentation, and nanomaterial applications. This approach gives students a sense of the nature of the nano

field and motivates students to pursue in-depth studies. Emphasizing breadth is particularly beneficial for beginning students because it offers them an early chance to “see” what attractive careers chemistry, science, and engineering may offer (15). Using a Hands-On Approach Science research suggests that the experiential basis comes before abstract understanding. It is based on the learning theory of constructivism (16), which holds that students participate significantly in the teaching–learning process as a result of relevant prior knowledge that they use to make meaning out of new experiences. This may explain why certain concepts such as volume and kinetic energy are more easily learned by students compared to mole, quantum numbers, or the structures of amino acids. A “hands-on” approach is an instructional strategy in which students work with materials, manipulate physical objects, and utilize scientific tools to physically engage in experiencing science phenomena. This approach involving multiple senses is often considered to be part of the developmental process of moving from concrete to abstract thinking (17), or the basis for learning. Hands-on activities can be structured with guidance and instruction (common lab activities). They can also engage students in systematic and in-depth investigations (inquiry-based or research activities). All are expected to provoke curiosity and thinking, with research aiming at creating new knowledge. Optimal learning is believed to occur when students reflect on or draw meaning from those experiences. Research studies (18–20) also indicate that hands-on learning improves students’ science process skills, such as handling chemicals and tools, making and recording observations, analyzing and interpreting data, and communicating results. These skills, allowing students to develop the ability to inquire on their own, are important to learning science. These studies also show that hands-on programs can enhance students’ science attitudes, and economically or academically disadvantaged students benefit the most from such an approach (18–20). Because of the abstract nature of nanoscience—namely, no one can “see” or “handle” matter at the nanoscale without specialized tools and processes—hands-on learning is important. At the nanoscale, new properties of matter become apparent and these properties also vary with size rather than remaining constant as they do at the bulk level. Learner intuitions thus are misleading and often hard to correct. The idiom, “seeing is believing”, means exactly that—people can only really believe what they experience personally. Students’ direct experiences with nanomaterials and phenomena offer ideal opportunities to challenge their present knowledge and facilitate their learning (21). The nano hands-on activities allow students to take with them the experiences, understanding, skills, and enthusiasm that can serve as the source for appreciating the broader issues they later encounter and provide them the aptitudes for exploring and discovery.

© Division of Chemical Education • www.JCE.DivCHED.org • Vol. 86 No. 6 June 2009 • Journal of Chemical Education

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Integrating Nano into the First Two Years of Chemistry Curricula This integration can be done using available courses and by developing new courses. Because nanoscience is an extension of existing sciences, it can be presented through established core chemistry curricula. This strategy affects a large number of science and engineering students because these cornerstone courses are part of these students’ curricular requirements and typically have large class sizes. Using existing courses therefore capitalizes on available infrastructure, provides a dependable method to institutionalize early nano education, and may potentially attract students with diverse backgrounds to the fields in which nanoscience is becoming increasingly important. Creating new courses allows students to gain added knowledge and skills advantageous to their professional advancement. These new courses will be described in a separate paper. Incorporating Nano in Established Outreach Programs The chemistry department at University of Pittsburgh at Titusville (UPT) has developed or participated in various service and outreach programs. Over the years, these programs have built a reputation for their excellent quality, outstanding educational value, and highly entertaining nature. Incorporating nano handson activities into these programs allows students to experience additional nano examples, gain teaching skills, and better understand newly acquainted concepts via teaching (21). It also allows

us to educate the public, especially students in grades K–12, about nanoscience. Programs exposing pre-college students to sciences and increasing their access to higher education can effectively increase the number of students choosing science and engineering as majors when they apply for college (22–24). Selection and Implementation of Nano Activities General Chemistry Laboratories Table 1 summarizes the activities used in general chemistry laboratories. The introduction and the scanning probe microscopy (SPM) seminars can be given during the first- and second-term laboratory check-in weeks, respectively. (SPM includes STM and atomic force microscopy—AFM). The former, a nanoscience overview, allows students to connect the nano activities they later engage in to specific nano areas. The latter allows students to learn about and observe how modern instruments work, providing students with the background for hands-on STM learning. (See Figure 11 for graphite surface images included in the STM demonstration.) The STM activity illustrates the quantum tunneling concept presented in the atomic structure chapter. The gold nanoparticle experiment (7) can be used after introducing oxidation–reduction reactions. This colorful activity illustrates the surprising, size-dependent optical properties of nanoscale gold particles and their uses as chemical and biosensors. Students are provided with gold nanoparticle STM

Table 1. General Chemistry Laboratory Activities Exploring Nanoscience Activity

Brief Description

Concepts and Skills Taught

Time/min

1

Seminar: Introduction to Nanoscience

An overview of nanoscience including its basic features, future, and job outlook.

Nanoscale science: size and scale; Surface and quantum effects; “Nano” phenomena; Synthetic and fabrication methods; Applications

60

2

Colloidal Gold (7)

Students synthesize red, purple, and blue gold nanoparticles, view their STM images, and explore their applications as chemical and bio sensors.

Nanoscale science; Redox reactions; Bottom-up approach: Colloidal chemistry; Size-dependent optical properties; Sensors; Lab skills

120–180

3

National Chemistry Week (NCW) Service Learning Program

Students work with 160 middle school students during a visit to the UPT lab. The project includes 30 NCW-theme related activities; nine are nanoscience activities.

Structures, properties, and applications of “nano” products; Teaching, mentoring, and lab skills

4

Seminar and Demo: Scanning Probe Microscopy

Students learn about STM and AFM and observe how STM images are obtained.

Enabling tools for “seeing” and manipulating at nanoscale; Quantum tunneling; How STM and AFM work

5

Aqueous Ferrofluid Nanoparticles (9)

Students synthesize ferrofluid nanoparticles, view their STM images, and explore their magnetic properties and uses.

Bottom-up approach: Colloidal chemistry; Intermolecular forces; Superparamagetic properties; Applications; Lab skills

6

Self-assembly of Soda Straws and Plastic Beads (10)

Students float soda straw pieces and plastic beads in water with careful agitation.

Self-assembly; Thermodynamics; Bottom-up approach; Factors that affect self-assembly; Lab skills

120

7

NanoPatterning with Lithography (11)

Using tablets of varied sizes and UVsensitive papers, students create various patterns.

Serial versus parallel nanofabrication; Nanosphere lithography; Self-assembly; Top-down and bottom-up approaches; Lab skills

120

706

180

45–60

120–180

Journal of Chemical Education • Vol. 86 No. 6 June 2009 • www.JCE.DivCHED.org • © Division of Chemical Education

In the Classroom

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Figure 1. Highly oriented pyrolytic graphite (HOPG) surface. A: STM images (0.1 s/line, 256 points/line); B: Image of a van der Waals surface generated using CAChe software.

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Figure 2. STM images of gold nanoparticles (0.1 s/line, 256 points/ line). A: Red—average size is 16 x 22 x 15 nm; B: Purple—average size is 25 x 40 x 20 nm; C: Blue—average size is 35 x 60 x 30 nm.

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Organic and Analytical Chemistry Laboratories Experiments used in organic chemistry and analytical chemistry laboratories utilize an STM. Early in the term, students in groups of three are given 1.5–2 hours to make a tip and obtain STM images of highly oriented pyrolytic graphite (HOPG) surface with atomic resolution. Students interpret these images (see Figure 1): the bright spots show high points and dark spots low points. There are two kinds of carbon atoms in graphite (25): one with a neighbor in the plane below and one without. The surface conductivity varies slightly so the atoms without neighbors appear “higher” or “brighter” than the others (26). The distance between two adjacent “high” points is 0.25 nm, agreeing with the literature. Students can generate a van der Waals surface profile of fused benzene rings (simulating graphite surface) using CAChe software (Fujitsu) and compare the profile with graphite surface images. Two additional experiments can be used in organic chemistry labs. One involves the synthesis, properties, applications, and STM imaging of polyaniline nanofibers. Students spend the first lab synthesizing the polyaniline nanofibers via interfacial polymerization (27). They then prepare polyaniline pH sensors (28) and STM samples. During the second and third labs, students (taking turns using the equipment) test the pH sensors

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images (see Figure 2). The images reveal the fairly uniform red gold nanoparticles with an average size of 16 × 22 × 15 nm. The literature value is 13 nm (7). As particles aggregate, both their sizes and size distributions increase, producing a color change, first to purple (average size of 25 × 40 × 20 nm) then to blue (average size of 35 × 60 × 30 nm). Each fall, we develop 30–40 hands-on activities highlighting the National Chemistry Week (NCW) yearly theme and incorporate these into a service learning project in the general chemistry laboratory. During the project, 160–400 local K–12 science students and their teachers are invited to perform these activities in our chemistry labs. The college students prepare by spending an hour learning all the experiments. They then work in shifts with the visiting students on 2–4 experiments. The visiting students form groups of 3–4 and spend 30–60 min rotating among stations. Recently, nano examples (see description in the Chemistry Outreach Programs section below) were used to demonstrate how control of the structure at the nanoscale can result in new or enhanced properties. The ferrofluid experiment (9) may be used after introducing solutions and colloids. The spikes formed when the ferrofluid is placed near a magnet fascinate students. Its potential use as drug carriers also interests them. Students are provided with the ferrofluid nanoparticle STM images (see Figure 3). The images show that these rather uniform particles (about 6 ×13 × 6 nm in size) tend to line up in an orderly fashion. The literature value is 14 nm (9). The self-assembly of straws and beads experiment (10) is introduced after the Gibbs free energy chapter. It demonstrates how enthalpy and entropy changes affect the process spontaneity at a given temperature. Students explore how and why some objects self-organize into ordered structures, a process found in nature for creating all living and many nonliving things. The nanolithography experiment (11) illustrates how self-assembly is used to create surface patterns at the nanoscale and how this leads to applications in fabricating semiconductor integrated circuits and nanoelectromechanical systems.

0 nm

70 nm

Figure 3. STM image of ferrofluid nanoparticles (0.1 s/line, 256 points/line). Average size is 6 x 13 x 6 nm.


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and obtain nanofiber STM images (see Figure 4). The second experiment involves forming an arachidic acid monolayer by selfassembly. Students propose the possible ordered 2-D structures based on minimizing the system’s energy. They then compare these structures with the monolayer STM images. The lattice model in Figure 5B matches the experimental results (Figure 5A). The length of arachidic acid molecule was measured as 2.7 nm and the intermolecular spacing as 0.5 nm, consistent with literature values (29). Students also practice imaging the monolayers (30).

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First Research Experiences Many UPT students gain their first research experiences through nanoscience-themed projects. The literature has shown limited STM images obtained using the affordable NanoSurf EasyScan 2 system, other than the graphite and gold surface images. The goal is to determine whether the EasyScan 2 STM could provide acceptable images for selected nanomaterials. A literature search is conducted to ensure the work is original. Students are asked to write a one-page proposal and a project

Figure 4. Scanning tunneling microscopy image of polyaniline nano fibers (0.1 s/line, 256 points/line). Average diameter is 8–14 nm.

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• A chart showing materials (natural and synthesized) at the macro, micro, and nano scales

• Nano solutions for the nano concept

• Liquid crystals as forehead and aquarium thermometers

• Gold nanoparticles for home pregnancy tests

• Ferrofluid for water purification and smart metals for eyeglass frames and orthodontic braces

• Liquid metal for home insulation, nanofibers for stainfree clothing

• Light-emitting diodes (LED) for energy-efficient home lighting

• Nano solar cells to produce cost-effective solar electricity

Imaging Using NanoSurf EasyScan 2 STM Selected images from the NanoSurf EasyScan 2 STM are shown in Figures 1–5 (additional images are in the online supplement). The STM tips are prepared mechanically from Pt–Ir wire with a wire cutter. A small amount of water soluble sample is dispersed in water. The water insoluble quantum dot sample is washed with methanol, precipitated in acetone, and dispersed in chloroform. One drop of the dilute colloidal solution is then delivered to the center of a HOPG surface in a Petri dish. The solvent is allowed to evaporate with the Petri dish covered. The tunneling parameters are set at 1.00 nA and 50 mV and the loop gain is approximately 900–1000. The scanning conditions are adjusted at 0.1 or 0.2 s per line and 128 or 256 points per line. For the monolayer experiment (30), arachidic acid is dissolved in phenyloctane and the monolayer formed on a HOPG surface. The Figure 5A images were collected with tunneling parameters of ‒0.5 nA, ‒1450 mV and ‒0.3 nA, ‒1240 mV. Program Outcomes and Assessments

arachidic acid hydrogen bond

Figure 5. Monolayer of arachidic acid. Literature values for arachidic acid alkyl zigzag chain length and intermolecular spacing are 2.7– 2.8 nm and 0.48 nm, respectively (29). A: STM images obtained with these parameters: 0.1 s/line, 256 points/line; left: ‒0.5 nA, ‒1450 mV; right: ‒0.3 nA, ‒1240 mV. B: Lattice model.

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Chemistry Outreach Programs Nano projects are incorporated into nine major chemistry outreach programs. This includes the Erie Mall Chemistry Show, in which UPT faculty and students participate in the presentation of chemistry displays and 20–30 hands-on activities to the public in the largest shopping center in northwestern PA. Other programs range from an NCW on-campus celebration to chemistry seminars for gifted high school students. The nano examples (8, 14, 31) reflect the 2006 NCW theme, “Your Home, It’s All Built on Chemistry!”:

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report. They work in groups of 2–3 and are required to update their progress weekly. The investigated nanomaterials include: gold nanoparticles; ferrofluid nanoparticles; quantum dots (12); nickel nanowires (13); and polyaniline nanofibers and their inorganic composites.

The program is evaluated by administering pre and post quizzes and open-ended survey questions to 60 participating students. This includes 18 research students as well as students in the courses having nano hands-on components. The results are described below. Nano Knowledge and Awareness Students’ increased knowledge and awareness of nanoscience is demonstrated by an increase in their quiz scores, typically


In the Classroom

from 0–50% (pretreatment) to above 70% (posttreatment). The quiz questions were devised to assess students’ learning of the key concepts in the activity. Students take the pretreatment quiz before the activity, then the topic is introduced and the key concepts are discussed. This is followed by the lab activity. The same quiz is given to the students after they have completed the lab. A set of survey questions is also used to evaluate the learning gain. Through these experiences, students have recognized the uniqueness of nanomaterials. Many students stated that they did not know nano-sized gold particles could be red, purple, or blue until they made them and saw their STM images. This has likely motivated them to learn why these materials do what they do and contributed to the improved scores on the question, “what makes the nanomaterials unique?” Students have learned about colloidal synthesis and realized the importance of self-assembly. The scores demonstrate their increased awareness of how factors such as size, shape, charge, and motion affect self-assembly and guided self-assembly, resulting in certain forms and structures (imparting certain functionalities). A STM demonstration after a SPM seminar allows students to visualize atoms. The scores show that students have grasped how SPM works: the STM shows images of atoms based on a constant tunneling current between the surface atoms and the probe tip (constant current mode) while an AFM is based on a constant attractive–repulsive force. Students have also learned the challenges associated with operating a STM (a sharp tip, conductive surface, and little interference). Their awareness of nano applications is assessed using the quiz on the NCW service-learning unit. An improved score is shown on questions relating to material properties and product applications. A posttreatment nano lab question asks students to list the existing and potential applications of the nano products through information searching, allowing students to further appreciate the possibilities of nanoscience. Specific Nanoscience and General Science Process Skills Science is a process. Its goals include investigating phenomena, acquiring new knowledge, and correcting and integrating previous knowledge. This process involves a set of systematic steps: define a question, gather background information, form hypothesis, perform an experiment (or experiments) and collect data, analyze and interpret data, draw conclusions, and publish results. Teaching students the skills essential to doing science is central if we want students to learn science. Many important science process skills, however, can only be achieved through doing science. There is no exception in teaching nanoscience, an exciting field of inquiry that has its special set of phenomena, tools, methods, and safety issues. One measure of students’ skill improvement is students’ ability to independently operate instruments used in nanoscience. This enables students to conduct research using these tools with minimal supervision. In three semesters, thirty students have obtained hands-on training on the STM and several of them have contributed to the STM image collection. Students go through the process of making and installing the tip to manipulating and storing the data. Although some students did not succeed in lab class (30–50%), they obtained good quality STM images during their later research projects. The hands-on experiences have made learning nanoscience “real”. Students get to work with the chemicals, set up the appa-

ratus, go through the procedures, and observe the actual effects of their doings. One student stated: The lab projects really interested me. For instance, we actually made titanium dioxide solar cells. When we held them up to the UV light, they actually worked! It was also interesting to see how different juices affect the cells causing the multimeter to have different readings.

Students can be taught in class how to make a nano solar cell and how the type or amount of chemicals affects the cell performance. They may understand the entire procedure, yet they would still not know how to build such a cell unless they go through the procedure and would unlikely display the same amount of enthusiasm. The experiences students gained from making nanomaterials utilizing unique synthetic and fabrication methods are invaluable. The experiences allow students to practice handling equipment and nano-sized materials properly and safely. Compared to the lectures, hands-on learning offers authentic opportunities for students to develop observation and reflection skills. In the self-assembly experiment, students float straw pieces and plastic beads of different sizes and shapes in water with slight agitation to visualize and understand how and why many atoms and molecules order themselves in nature. They are asked to sketch their observations and provide reflections. Some of the comments include:

I learned how things want to stick together.

I learned how the short straws tend to line up end-to-end and the long ones side-by-side.

I was able to move the pieces into a more ordered pattern by swirling the water slightly and carefully, but I was not able to make it perfect. I guess defects are inevitable.

Things want to order themselves and stick together—this is the theme revealed by the STM of almost all of the nano systems we studied. The careful experimentation, observation, and thoughtful reflection provide means for learning, knowing, and discovery. Engaging students in research is the best way to teach science. Students experience the science process (entirely or in part) aiming at creating new knowledge. Students learn that scientific discovery often comes from failures. They learn whatever they try to do in the lab will usually not work the first time. Research presents students the opportunity to develop all the process skills, including problem solving, with a purpose of achieving the goal of doing science. Among the skills, students identify keeping a lab notebook as the one from which they have gained the most. Research allows students to experience additional nanomaterials, synthetic methods, and lab techniques. Most importantly, it provides them an exceptional chance to contribute to nanoscience, as demonstrated by the original EasyScan2 STM images collected with these students’ participation. The STM images reveal the presence of ultrafine nickel nanowires (10–15 nm in diameter) and polyaniline fibers (8–14 nm in diameter). The reported average diameters for nickel wires are 200 nm (13) and for polyanilnine nanofibers 30 nm (27). Our values for nickel wires closely match the alumina membrane pore diameter, which is 20 nm. Because the wires grow in these pores, the larger diameter nickel wires likely result from the self-assembly of the finer ones.


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Moreover, kinesthetic learners really benefit from handson learning. They are enthusiastic about the projects and often outperform many students who do better on a typical penciland-paper test in terms of the thoughtfulness and the ability to handle things and deal with problems, leading to more accurate and precise results. The experiences and confidence derived from the success help these students become better learners. Even students with low academic abilities in the traditional sense have a chance to succeed. One student who did not pass any tests and often skipped classes never missed any labs, was fully engaged in each lab or the group research project, and produced lab reports and a lab notebook that demonstrated learning, appreciation, and interest in nanoscience. The outreach programs provide students the opportunity to gain added knowledge in nanoscience, illustrate what is important in chemistry, and practice their communication skills through teaching, mentoring, and caring for others. Students take pride and responsibility for showing how to do the experiments and why they work. Students act as excellent role models for younger students and help bring the excitement of nanoscience to a large number of community members. Many students enjoy the activities so much they have volunteered for multiple sessions of the programs. Chemistry Attitudes Positive attitudes, as outcomes of chemistry instruction, stimulate interest and motivate students to learn. The open-ended survey feedback reveals that students appreciate the opportunities to be engaged in the nano activities. When asked whether the nanoscience learning helped improve their chemistry attitudes, a resounding 95% said “yes” (5% did not comment). They stated that nano research and lab experiences helped them see the possibilities of nano, motivated them to learn more about chemistry, and strengthened their interest in a career in science or engineering. Other Benefits Through hands-on outreach efforts we have exposed thousands of community members, mostly students in grades K–12, to nanoscience. This has allowed us to demonstrate how science and technology positively impact our lives and encourage the next generation to consider chemistry as a profession. All the programs have received positive feedback. For instance, for the service-learning program, more than 95% of the participating middle school students indicated that they found the program particularly beneficial in terms of learning science through a hands-on approach, being introduced to a college environment, and being able to interact with college students. Students also expressed their interest in a chemistry career and their excitement about learning contemporary science and technology. These efforts allow the community to benefit from the university resources and help increase the university’s visibility. Conclusion The assessment results show that our strategies have helped beginning college students increase their awareness and knowledge of nanoscience, gain STM and nanomaterials experiences, practice science process skills, and enhance their attitudes toward chemistry. The program strength lies in its hands-on nature that has made learning nanoscience “real”, allowing students 710

to experience nano phenomena and acquire nano skills. Kinesthetic learners and students with low academic abilities in a traditional sense may especially benefit from this approach. The concrete nanoscience experiences will help students make meaning out of new experiences they may later encounter. The first experiences in research help students learn how science is done and offer them an extraordinary opportunity to contribute to nanoscience. The outreach programs foster students’ development through teaching and caring for others while gaining new nano knowledge. Other program features include its inclusiveness, adaptability, and affordability. The program has reached a large number of targeted students (science, engineering, and precollege students) and community members. The broad coverage provides students an early opportunity to see the exciting careers chemistry, science, and engineering may offer. The activities utilize commonly available and affordable chemicals and equipment (the cost of the NanoSurf EasyScan 2 STM is about $15,000), facilitating easy adaptation. Efforts are underway to integrate additional nano activities into the second-year-level courses and design more sophisticated and quantitative assessment plans to better evaluate students’ learning outcomes in all three areas— nanoscience awareness and knowledge, specific nanoscience and general science process skills, and chemistry attitudes—that are unique to chemistry and nanoscience education. Acknowledgments The author would like to thank Joseph Grabowski for his many insightful suggestions and helpful discussions on the project design and implementation; Linda Winkler and Kelly Neidich for their encouragement and support; the manuscript reviewers for their invaluable comments; and Sarah Wuzbacher, Joseph Hartshorne, Garrett Britton, Yori Snyder, Anthony Talerico, Thiezue James, Ashley Clement, Palmer Wetzel, Jason Amsler, Brian Williams, and all the participating students for their enthusiasm, diligent laboratory work, and contribution to the STM image collection. The author is grateful to the Advisory Council on Instructional Excellence at the University of Pittsburgh for funding the project through the Innovation in Education Awards Program. Note 1. The figures in this paper are selected images collected using a NanoSurf EasyScan 2 scanning tunneling microscope (Nanoscience Instruments, Inc., Phoenix, AZ). If not otherwise specified, the tunneling parameters pertaining to each figure were 1 nA and 50 mV with loop gains of 900–1000.

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Supporting JCE Online Material http://www.jce.divched.org/Journal/Issues/2009/Jun/abs705.html Abstract and keywords Full text (PDF)

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STM images and a PowerPoint presentation on nanoscience

Five quizzes for students


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