The human brain is a very interesting and mysterious area to study. Memory capacity fluctrates between different people.
Some people are just better at remembering then others.
The best way to go aabout this project is to get a huge sample size and average results. Humans are hard to test because of their diverse capabilities and levels of learning. You would be better off testing more simplistic organisms such as mice or gold fish. As always, start as early as possible to obtain a high sample size and time to sort out data. To continue work on this project, I would also give another memory test during the day to compare the memory lost while awake and the memory lost during sleep.