I have a few suggestions for things to look into to improve comprehension of questions and using the calculator. Firstly, some units seem to use 2 variables that are very similar in appearance over 2 completely different ones. U and V are an example of a combination I've seen often. Secondly, I feel that in math, making a question tricky rather than harder is a way to artificially increase the difficulty. For example, the line of the first function on a graph is expected to correspond to the first equation that is shown. Flipping them does increase difficulty, but it does not do so because of the math. Thirdly, I don't think there is a wide enough variety of questions, at least as far as Algebra 1. I've answered several duplicate questions. Fourth, there seems to be an issue with what is counted as right. I have been impressed so far by the flexibility, but the Algebra 1 function unit seems to be less flexible. Lastly, the division and addition button on the calculator are very hard to tell apart. I still love this site and want to thank everyone who is a part of making it run. Thank you guys so much!