My radishes have germinated in two days, they grow quickly and you can eat them after about 3-4 weeks. The interest might come from seeing the red tips emerging from the soil against the bright green foliage? Dunno, just a thought, I'm no artist. Alternately, when I was little we sprouted bean seeds in jam jars with blotting paper curled on the inside to keep the bean in place and allow the plant access to the water. Seeing roots and leaves developing was fascinating.
G xx