Revising functional groups with lightbulb feedback

I’m always a little envious when people tell me they were students of chemistry at Glasgow during Alex Johnstone’s time there. A recent read from the Education in Chemistry back-catalogue has turned me a shade greener. Let me tell you about something wonderful.

The concept of working memory is based on the notion that we can process a finite number of new bits in one instance, originally thought to be about 7, now about 4.  What these ‘bits’ are depend on what we know. So a person who only knows a little chemistry will look at a complex organic molecule and see lots of carbons, hydrogens, etc joined together. Remembering it (or even discussing its structure/reactivity) would be very difficult – there are too many bits. A more advanced learner may be able to identify functional groups, where a group is an assembly or atoms in a particular pattern; ketones for example being an assembly of three carbons and an oxygen, with particular bonding arrangements. This reduces the number of bits.

Functional groups are important for organic chemists as they will determine the reactivity of the molecule, and a challenge for novices to be able to do this is to first be able to identify the functional groups. In order to help students practise this, Johnstone developed an innovative approach (this was 1982): an electronic circuit board.

Functional Group Board: Black dots represent points were students needed to wire from name to example of functional group
Functional Group Board: Black dots represent points were students needed to wire from name to example of functional group

The board was designed so that it was covered with a piece of paper listing all functional groups of interest on either side, and then an array of molecules in the middle, with functional groups circled. Students were asked to connect a lead from the functional group name to a matching functional group, and if they were correct, a lightbulb would flash.

A lightbulb would flash. Can you imagine the joy?!

Amide backup card
Amide backup card

If not, “back-up cards” were available so that students could review any that they connected incorrectly, and were then directed back to the board.

The board was made available to students in laboratory sessions, and they were just directed to play with it in groups to stimulate discussion (and so as “not to frighten them away with yet another test”). Thus students were able to test out their knowledge, and if incorrect they had resources to review and re-test. Needless to say the board was very popular with students, such that more complex sheets were developed for medical students.

Because this is 1982 and pre-… well, everything, Johnstone offers instructions for building the board, developed with the departmental electrician. Circuit instructions for 50 x 60 cm board were given, along with details of mounting various plans of functional groups onto the pegboard for assembly. I want one!



A. H. Johnstone, K. M. Letton, J. C. Speakman, Recognising functional groups, Education in Chemistry, 1982, 19, 16-19. RSC members can view archives of Education in Chemistry via the Historical Collection.

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