There are several good sites like this one that talk about breeding roses. Google "rose hybridizing". You might want to consider another plant if he needs to show actual results. It will take a year or more for your rose seeds to develop, germinate, and flower.

Yes it takes a year or more to go from pollination through seed, seedling, and first bloom. I collected rose seeds last september or october and although I got a dozen to sprout, only one has flowered so far, and a second is aking it's first bud. Also, you have better control over breeding a plant which can be grown inside. I would recommend a fast-growing easy-to-care-for garden vegetable, perhaps beans since they are available in several colors. Gregor Mendel did his famous breeding experiments on peas if I remember correctly.

Lucretia1,
Thank you for your response. Benny and I researched roses yesterday and found that it takes four months for the seeds to mature. They wouldn't be ready for the science fair. He justs wants to demonstrate the effectiveness to pollinate using cross-pollination vs. self-pollination.

Sunandshadow,
Yes, somebody else suggested peas. Benny and I are going to research them today. I appreciate your suggestions and ideas. Thank you.