I got some more new ideas, but they're all a bit weird.
Do frozen seed sprout?
What type of plastic wrap prevents evaporation best?
How permanant are 'permanant' markers? What will dissolve the ink?
Is a seed affected by its size?
Does the amount/absence of light spoil food slower/quicker?

Okay now I think I have enough ideas to get me started. Now, I just need to finalise them and pick the best one that I'd enjoy the most. Hmm... What to do what to do?