Anyone else try to have the boys write poetry?

I find that most of the time, they rhyme very well but will always default to AABB. When I ask for ABAB, 85% of the time they will still generate in AABB format. I have asked them to define and explain the difference between the two rhyming schemes and they know the difference by definition. Today, I had them explain the difference between AABB and ABAB rhyme scheme first, then provide me an example of each one. They gave flawless definitions and yet, both examples were AABB. Makes me want to pull my hair out, lol.