Cell Size and Scale, an elegant and deceptively simple interactive from the University of Utah's Genetic Science Learning Center, enables you to compare the sizes of various really small things. The interactive is available free on the Internet and works on desktop computers, smart phones, and tablets.
A microscope is to see smaller things that you can’t see and it is a really good tool.
The outcome will be 25% homozygous dominant, 50% heterozygous, and 25% homozygous recessive. so a 75% chance they will have round seeds and a 25% chance they will have oval seeds.