If you are math savvy, I would say you could do it without the TM's. Of course, you'd have to do all the calculations when correcting, and that would really be a pain. I am using Horizons 4 this year, and the thought of correcting without a cheat sheet makes me shiver! I find the TM helpful when teaching new concepts. e.g. He began learning about prime numbers this week. I would have had a difficult time without the TM. Almost everything up to this point I could teach without it, though.