My students always tend to get mixed up when using the Pythagorean Theorem Converse. They tend to get the direction of the inequality mixed up and I hear things like "greater than means acute...or does it mean obtuse?". My solution to this is to have students ALWAYS write the bigger number first in the inequality and put a box where the inequality goes. So they would write something like this...
52 o 32 + 42
Then, they do the comparison to see which is larger. Basically, they are being consistent with the way they are showing their work. I try to get them to say to themselves, "The longest side is longer/shorter than the other two, so that means it's acute/obtuse." I think consistency helps them in this case.
Here is a practice activity for interactive notebooks using the Pythagorean Theorem Converse.
I like this because they are doing a zillion practice problems, but the students don't really notice. I glued everything in on this page, but I could have made little pockets and put the cards in the pockets so students can practice. You can find this activity here.