I don't know how well this puzzle will translate to a toot. Imagine each line is on a card:

□□▷
□□□
■■
■
□■
□▷▣
▣
□▣
■▷
■▣
▣▷
□□■
□▷
▣▣
□□
□
▣□
□□▣
■□
▷
□▷□
□▷■
▣■
□▷▷

Put them in order.
(The 5th graders could do it, but they did have a helpful example first... There may be more than one solution, but I think there is ONE really good order. Can you find it?)

(I should also mention that every adult I've shown this to gives up. But I only showed it to two rather grouchy teachers.)