Designing a natural selection experiment - (May/09/2015 )

you have rich grand -mother and wants to learn how natural selection works in nature.Design an experiment to show her how natural selection works in your experimentYour experiement can take maxşmum 1 year to complete and spend as much as money as you want.)

here you are, you need just two aquariums, gravel and some guppies:

http://evolution.berkeley.edu/evolibrary/article/artificial_01

Thanks :)