Like Leo, Henry doesn't catch on right away like his siblings as mom teaches them to play dead. He also has a tendency to hum that any early childhood educator will recognize in at least one student per year (probably more).
And like P. D. Eastman's character, Henry get separated from his mother and finds himself searching and asking "Are you my mother?" The repetitive pattern helps reinforce questions and question marks for students. It is also another good book for finding repetition with the sight words are, you, or my.
So, if you've used either Leo The Late Bloomer or Are You My Mother in lessons in the past, consider trying Henry Possum, either to compare and contrast or to try something new. And by new, I mean old. But good. Enjoy!