Chemistry for Everyone
Sudoku Puzzles as Chemistry Learning Tools
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Thomas D. Crute* and Stephanie A. Myers Department of Chemistry and Physics, Augusta State University, Augusta, GA 30904; *
[email protected] The chemistry curriculum still includes some material that requires rote memorization, often including distinctions between superficially similar items. Mastering such material is seldom exciting and many students are reluctant to perform these tasks. Therefore, a method that would make these tasks more interesting is desirable. There are several examples of puzzles being used in the classroom including wordsearch (1), letter matrix (2), and crossword (3) puzzles. We have developed sudoku puzzles that use chemistry terms in such a way to meet this goal. Sudoku puzzles have become quite popular in recent years and routinely appear in media such as newspapers, puzzle books, Web sites, or can be created through available software (4, 5). The most common puzzles use numbers one through nine in a 9 × 9 grid that is subdivided into 3 × 3 boxes, although different sized grids and characters other than numbers have been used. A completed puzzle has one instance of each number or symbol per row, column, and box. A limited number of symbols are strategically placed in the grid as the “givens” for a starting point, and the puzzle solver must use logic to determine which symbol should appear in each of the remaining spaces. The easiest puzzles only require simple logic or solving by inspection, while progressively more difficult puzzles require more sophisticated or multistep analysis and problem solving. A combination of ruling out symbols for a particular space to avoid repetition, and determining which symbol is still needed in a particular row, column, or box is a typical strategy of solving by inspection. The Royal Society of Chemistry has a chemistry sudoku puzzle that uses symbols instead of numbers and includes element symbols and isomers of heptane (6); however, these symbol-based puzzles do not have the learning element that our puzzles have introduced by mixing names with structures or specifically picking easily confused terms as puzzle symbols. A hallmark of solving a sudoku puzzle is the reliance on careful attention to which symbols are already present in a given row, column, or box. A second feature is the repetition involved in examining the details of the puzzle during the solving process. These characteristics prompted us to design sudoku puzzles that incorporate lists of chemistry terms that students need to know, such as polyatomic ions, organic functional groups, or strong nucleophiles. It was believed that the repetition involved in solving the puzzles would aid in memorization of these items. Furthermore, easily confused symbols that are superficially similar but different upon closer inspection, such as sulfate and sulfite polyatomic ions, would be ideal candidates for inclusion since students must attend to the details of each symbol to ensure no repetition. Mixing structures and names within the same puzzle demands that students pay attention to these correlations. With these characteristics in mind, puzzles were designed that included both names and structures so that the correlation between them must be made by the puzzle solver. Figure 1 shows a puzzle based on functional groups that includes the names, complete structures, generalized structures, structural variations such as both pri612
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mary and secondary amines and structural abbreviations for aldehydes and carboxylic acids that force students to recognize allowed variability in conveying these structures. Two additional puzzles—one based on polyatomic ions and one based on nucleophiles—are included in the Supplemental Materials.W Creating the Puzzles Since the learning goal was increased usage of and attention to detail for the symbols themselves (rather than the problem-solving logic of the puzzle), the easiest puzzles available were chosen such that they could be solved solely by inspection. The difficulty level for a puzzle often accompanies published puzzles. To transform a numerical 9 × 9 puzzle to a chemical one, an instructor must generate a list of exactly nine chemistry items or symbols. Each symbol is assigned to one of the numbers that appears in the puzzle and the numerical “givens” are substituted with the corresponding symbol or symbol name. We used a chemical drawing program (7) to build a blank 9 × 9 grid from which each individual puzzle could be created. An additional feature can be used that takes advantage of the experience we have as puzzle solvers. Before making substitutions, the puzzle was solved in such a way that all nine instances of a particular number could be completed before going to the next number so that the chemistry puzzles could include a suggested order of solving to reward students with the appropriate chemical knowledge. Thus a hint is given for the functional group sudoku shown in Figure 1 that if the symbols are filled in starting from the highest to lowest priority group in IUPAC nomenclature (8), then the puzzle will be solved more readily. Thus the solver should start with the carboxylic acid functional group. An examination of the top middle box of Figure 1 reveals three blanks and six “givens”. The upper-left blank should be filled in with a carboxylic acid since the remaining two blanks in that box already have a carboxylic acid listed in those rows. If students were to randomly choose a different first functional group, they would likely find that more than one possibility for a certain space and solving the puzzle would take more time and effort. For instance, attempting to start with an aldehyde or amide in the top middle box would only allow the solver to narrow the possibilities to two of the three blanks, rather than definitively filling a blank. Therefore this strategy of providing chemical hints rewards those with appropriate chemical knowledge. Results Informal student feedback indicates that assigned puzzles were generally helpful in learning the chemistry and were more enjoyable than traditional rote methods of memorization. Some students said the puzzles forced them to learn the chemistry faster than they would have otherwise. There were a number of students who had seen, but never solved, a sudoku puzzle before and were thankful to know what they were and how they worked. To date our use of sudoku puzzles has been
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Chemistry for Everyone
Figure 1. Functional group sudoku. Answers are available in the Supplemental Material.W
to offer them as optional, take-home assignments that are collected at the next class period. As motivation to complete this optional assignment, students who complete the puzzle are then exempt from the quiz covering the same material present on the puzzle. The puzzles can be graded by examining a handful of squares to ensure that the proper symbol is present, as a mistake in one location usually results in several misplaced symbols. When the puzzles are assigned, a few minutes of class time can be used to show the necessary strategy, while a link on the class Web site to puzzle-solving guides can assist students outside of class (9). In our experience most students actually used the chemical symbols to solve the puzzles. In rare cases evidence suggests that students have assigned numbers to each symbol, solved the puzzle with numbers, and then taken the solved numerical puzzle and filled in the appropriate symbol. Such a strategy defeats the stated learning purpose of the chemistry puzzle whereby students were to benefit from the repetition of working with the chemical symbols and names.
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Supplemental Material
The answer to the functional group sudoku and two additional sudoku puzzles and their answers (anions and nucleophile) are available in this issue of JCE Online. Literature Cited 1. 2. 3. 4.
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Conclusions Students appreciate “fun” ways to do boring tasks such as memorizing fundamental chemical vocabulary. Sudoku puzzles provide such a method. The ready availability of puzzle templates and the ease of making substitutions allow this assignment to be incorporated in the classroom with minimal effort. To create puzzles with a suggested order of completion requires more preparation time and some expertise in puzzle solving such that good suggestions can be provided. www.JCE.DivCHED.org
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Helser, T. L. J. Chem. Educ. 2005, 82, 552. Kelkar, V. D. J. Chem. Educ. 2003, 80, 411–413. Most, C. J. Chem. Educ. 1993, 70, 1039–1040. Sudoku Home Page. http://www.sudoku.com/ (accessed Jan 2007); provides puzzles to many newspapers and sells software for Windows computers that will create a sudoku puzzle. Web Sudoku Home Page. http://www.websudoku.com/ (accessed Jan 2007); contains nine-by-nine as well as alternative grid sudoku puzzles. Riddick, D. Chemistry Su Doku; RSC Publishing: Cambridge, 2005. ChemDraw Ultra version 7.0 by CambridgeSoft. http:// www.cambridgesoft.com/software/ChemDraw/ (accessed Jan 2007); used to construct both the grid and the chemical symbols. Priority of organic functional groups is normally listed in introductory organic chemistry textbooks such as Bruice, P. Y. Organic Chemistry, 5th ed.; Pearson Prentice Hall: Upper Saddle River, NJ, 2007; p 791. Wikipedia: Sudoku. http://en.wikipedia.org/wiki/Sudoku (accessed Jan 2007); describes numerous logic methods for solving a sudoku puzzle.
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