Me: Right handed, right thumb
Number 1 Kiddlet: Right handed, right thumb
Number 2 Kiddlet: Right handed, left thumb
Hubby: Right hand, right thumb
My son's project last year was "Does sugar increase your short term memory?" He had fasting subjects look at ten 6 digit numbers, wait 5 minutes, and rewrite them. Later he had them drink a can of lemonade, wait a half hour and take the test again with different numbers.
I was shocked at how much more I could remember after a sugar load. 2 the first time, 7 the second. It made a big difference for most people.
Little did I know those donut laden all nighters in college led to my grades to be dependent on my donut intake!
Did he try reversing it, doing the sugar-loaded trial first? Or do two trials, without sugar loading, to test the effects of practice?
Another fun variant is doing backward digit-span tests, where they have to repeat the sequence in reverse. This ties into mental processing rather than just memory.