Knewton alta

Pros: Some of the tools they use for the graphing questions are cool and allow you to move points around the graph without having to painstakingly put in each and every one. If you want to do a lot of busy work or have students learn nothing, then its perfect for you.

Cons: The instruction is poorly written and questions are repetitive. It doesn't help you learn or teach you anything. Teachers aren't able to change the questions or the focus of the homework so Knewton just does whatever. Half of the homework's are overly simple and don't test skills or help with comprehension. The other half are overly complicated and also a complete waste of time.

Overall: It could cost $1/year and it still wouldn't be worth it. Don't waste your time, money, or energy on something as worthless as Knewton Alta. I have only been using it for the past few months for my math class but every time I use it, I want to bash my head into the wall. I have done 17 homework assignments and only about 3 of them were helpful. Homework problems of trig and sin/cos/tan were overly simple and asking for simple ratios rather than having you solve or simplify equations. A lot of questions are in the same format but with slightly different numbers. I understand that repetition can help you learn but I feel that it will frustrate and confuse students even more because they will take one look at a problem in a class or on a test, see that its not in the exact same order, and think they don't know how to do it. It requires zero critical thinking. It spends a significant amount of time on equations that are barley ever used/that you can solve things without (I am currently taking Pre-Calc at a community college but have taken Pre-Calc and Calc I in high school). It is a huge waste of time and I don't recommend it for anyone, ever.

If you actually want something helpful, use Khan Academy
(This isn't sponsored, and I have no affiliation with them. Just a student who has used both and can see a clear difference)