I got a new student in the middle of this year who is in DESPERATE need of some feature function class knowledge! This is a foundational skill that I like to teach in discrete trial format, but usually requires a little pre teaching and language to make it work. 
Each book has the option of matching the word/ picture, label, or class name… so there is easy differentiation for any level or students I may have. The books are aligned well with my other adapted books, making it easy for my students to learn this new skill in this format!
I started off by only creating the basic categories!
1. vehicles
2. animals
3. food
4. people
5. clothes
6. places
7. furniture
I felt that these words and categories were most functional for my lower level students!
You could easily work with objects and these categories, too, if you think your students would better respond to tangible objects. I’ve found these little toys from amazon (affiliate link) or even the Target Dollar Section!
Thank you for the helpful advice, I like finding things like this and make a little database for when I get my classroom. I will certainly be adding this.