1 Assessment of Organic Chemistry Students Utilizing Molecular Modeling Images: Quiz Results of Multiple Choice and Explanation Questions. Julie B. Ealy and Jim Hermanson Penn State University Berks-Lehigh Valley American Chemical Society Anaheim, CA – March 2004

2 Multiple Molecular Images in Organic Chemistry CD – 3D molecular images that can be manipulated Molecular modeling software Physical ball and stick models Textbook – ball and wire; space filling; line drawings; “wedge” images Online images that can be manipulated

3 Cognitive Theory of Multimedia Learning Mayer, material presented in both pictorial and verbal form Process pictures and words in sensory memory visually and auditorily – promotes active engagement in learning – contributes to transfer of knowledge Assessment through use of molecular images and questions not previously encountered in class Was there a transfer of knowledge?

4 Cyclohexane Quiz

5 Hydrogen 1 and 2

6 Rank: most eq to least eq

7 Ranking of structures C & D – preference for equatorial

8 Explanation of ranking Explanation scored as correct or incorrect nMean Overall mean = ANOVA = 1.798p =.175

9 Explanation: ranking, correct 59.68% (37) - Branch group larger: more hydrogens, more atoms 17.74% (11) - More room needed, larger groups cause more crowding 12.90% (8) – Stability: more stable if farther away from cyclohexane 12.90% (8) – Strain: the larger the molecule the more steric strain; more carbons and hydrogens on C – there is more steric hinderance

10 Explanation: ranking, correct 6.45% (4) – Repulsion: larger groups exert more repulsive forces 4.84% (3) – Electron cloud: Since C has more electrons, it would prefer the equatorial position where it can be further away 1.61% (1) – Energy: Groups such as C and D have large electron clouds and molecules containing these groups are most energetically stable when the groups are far apart from other atoms

11 Explanation: ranking, incorrect 29.03% (18) – Double bonded: harder for it to get where it wants to be; has no rotational ability; locked into place by pi bonds 8.06% (5) – Stability: D is more stable; C is more stable; C & D are more stable than A & B 6.45% (4) – Energy: more in C; more in C & D; D wants lower energy

12 Explanation: ranking, incorrect 6.45% (4) – NC: D would want to be closer due to sp2 orbital of C more readily than C’s sp3 orbital of carbon 4.84% (3) – Strain: The steric hinderance is not as great with a double bond. 3.23% (2) – Branch group larger 1.61% (1) – Repulsive forces and Electron cloud

13 Stereoisomer Quiz

14 Representation of the structures

15 If stereoisomers, then…

16 Explanation – If stereoisomers, then why? Explanation scored as correct or incorrect 50.00% correct (7) 3, no response Mean = Correct responses 50.00% (7) – different spatial arrangement 42.86% (6) – same formula % (3) – same structure 21.43% (3) – mirror images

17 Explanation: stereoisomers, correct They are stereoisomers because they have the same formula and same structure except the OH groups on the 2 nd and 3 rd carbons could not possibly be manipulated to match each other without breaking any bonds Same molecular formula, same connectivity, different spatial arrangements

18 Explanation: stereoisomers, incorrect Compounds are mirror images of each other (incomplete) These images are not a mirror reflection of each other, although they have the same molecular formula. The H’s off of C-2 in the first picture are in the axial position, one equatorial in picture 2.

19 Equivalence Quiz

20 Unique carbons?

21 Equivalent sets of hydrogens?

22 Explanation – structure A Scored as correct or incorrect Mean = 1.500n = 14 Correct, 50 %, (7) - equivalent sets of hydrogens were listed by number; one student circled the 3 equivalent sets - There are 3 equivalent sets of hydrogen. There are 3 different environments in which hydrogens occur. Because of the double bond this occurs.

23 Explanation – structure A, incorrect a % (4) – 1, 2, 3, 4, grouped as one set and 5, 6 grouped as a second set b. 7.14% (1) – unclear answer Carbons 1, 2, 3, and 4 have sets of 2 H c % (2) – no response

24 Reactivity Quiz

25 Order of increasing reactivity

26 Alkyl halide description

27 Transfer of knowledge? Equatorial vs. axial * Yes – greater than 60% responded correctly on the three quiz questions Stereoisomers * Yes – identification of molecular images as stereoisomers - > 76% 41% identification of molecules as enantiomers 50% explanation of images as stereoisomers

28 Transfer of knowledge? Equivalence quiz * No – 0% - uniqueness of carbons – no axis of symmetry created difficulty Yes - equivalent sets of hydrogens >57% - axis of symmetry Explain hydrogen sets – 50% Reactivity * No – 37 % - perhaps attributed to reacting substances Yes – 100% - identification of 1 o, 2 o, 3 o

29 Further Study Write new multiple choice questions Rewrite some existing multiple choice questions utilizing students’ conceptual errors Write alternative fixed response questions (Johnstone & Ambusaidi, 2001) utilizing students’ conceptual errors Rewrite multiple choice questions based on ambiguity Continue to increase sample size