Tonight we were reviewing "don't stand on your friend's blood" and then I was trying to think of a different mitzva to do. Immediately prior, I had spent a lot of time learning with Jack (age 4) who was so excited that he's old enough to learn Torah, too, and he chose hilchos Shabbos and we were running through what he knows about Shabbos and then I asked why Hashem made Shabbos and they were pretty stumped. It was good learning but explains why Elazar (age 6) was already kind of worn out by the time it was his turn (he was participating with Jack).
I didn't realize it, though, so I said, how about Maakeh? Elazar repeated it and I said it again so he would get the correct pronunciation. Then he got silly and when I said, "So what is the mitzva of maakeh?" he said, mimicking the exact intonations I used, "So chicken chicken the chicken of chicken?" and then he cracked up. I didn't realize at first what was happening and said, "Do you want to learn the mitzva of maakeh?" and he said, "Chicken chicken chicken chicken chicken?" and cracked up some more. At that point I realized that he was fatigued from learning and didn't want to learn anymore.
Although this doesn't come up that frequently in home school with individualized learning and small ratios and tailored lessons, I think it happens that boys (though girls, too) have a hard time realizing they are fatigued and are not able to express it. So they stop paying attention, lose focus, or start acting silly.
There have been so many times where I felt a lesson was very much within the capacity of my child. But my child communicated otherwise--whether by fidgeting, not focusing, being silly, refusing to do the work, or tantrumming. It's always a very tough balancing act when to push them that little bit harder because it teaches them to persist through it and achieve, vs. when it's time to reevaluate the lesson or the way it's being presented or the duration or the type of work you are asking them to do. Listen to your gut. You won't get it right every time. But over the course of thousands of interactions, you get a sense.
Silliness is a big indicator to me that my child is overloaded. I like to take 5, cuddle, be silly together, have a good laugh, and regroup later.