Depth of Field: A Card-Sorting Study for Organic Chemistry

July 23, 2018
Teaching & LearningJulia Winter
Ripples by Niklas Een (1)

When you quickly look at the image above you see black-and-white static, not unlike what you would see on an old TV from the 60s. (Yes, dating myself.) If you take the time to really study the image, focusing intently on the center, three-dimensional patterns and contours will appear. Over time you will be able to recognize these hidden images more quickly because you have had practice in the viewing of these kind of stereogram images.

What do these amazing three-dimensional pictures have to do with Mechanisms? 

A recently published JChemEd article from the Flynn group at University of Ottawa (2) researched the difference between students and professors and how they view organic chemistry reactions.

This study used a set of cards that showed reactions in the commonly used format of organic starting material followed by an arrow with other reactants and conditions (see examples of the cards below). Individuals from different groups (undergraduate organic chemistry students, master’s level and PhD-level graduate students, and professors) were asked to sort the reaction cards in a way that made sense to them. Each person was then given another set of cards and asked to place these new reactions into their existing sets.

The Flynn group used a method called Gephi network analysis (3) to compare the patterns of the reaction card sets. The images from this analysis immediately made me think of stereograms! The students’ network showed many different overlapping, seemingly random patterns, but with the professors’ definite structures became apparent – a couple of stars and a diamond.

‍Figure on left is the Gephi network analysis of the student grouping of reaction cards, image on right is the Gephi analysis of professor grouping for the same cards.

When viewing the reaction cards, undergraduate and Master’s level students grouped by structure and more surface level features such as whether the reactant had a carbonyl group or a metal atom, whereas the experts, both PhD students and professors, perceived a deeper meaning to reaction cards with a more mechanistic view of the static reactants and reaction conditions. 

This depth of field comes with experience: where undergrads see black-and-white, flat images of reactions; chemistry experts see energy, three-dimensions, and even movement.

One of the professors in the study discussed the fact that students need taught to read organic reactions and mechanisms like comics, that “the pictures tell the story.” The implications are that we need to guide students in understanding this image-rich story of chemistry and give them the feedback to discover the patterns within the images.

“Students will not know what is useful or where to focus their thinking without guidance. That said, simply telling the students what features to pay attention to could lead to memorization.”

Once I learned to see the three-dimensional images within the stereograms, I could not stop seeing those images. And I could use this new skill to discover all sorts of other hidden pictures within other pictures.

That’s our goal in teaching chemistry – to help students to see and even feel the flow and patterns that we, as experts, recognize when viewing organic chemistry reaction mechanisms, and then apply this new sight to new reactions.



1)    To view more of Niklas Een stereogram images, go to this website:

2)    A Comparison of How Undergraduates, Graduate Students, and Professors Organize Organic Chemistry Reactions.Kelli R. Galloway, Min Wah Leung, and Alison B. Flynn. Journal of Chemical Education 2018 95 (3), 355-365. DOI: 10.1021/acs.jchemed.7b00743

3)    Bastian, M.; Heymann, S.; Jacomy, M. Gephi: An Open Source Software for Exploring and Manipulating Networks. Third Int. AAAI Conf. Weblogs Soc. Media 2009, 361– 362

Co- Author

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