I am looking for a software or site that will allow students assist each other on homework questions online. It would a type of mini-forum but dedicated to students of one class, in say calculus. My hope is that the collaboration will bring the class level higher. A user friendly version of math.stackexchange.com would be nice but it should for students of one class in order to mobilize interaction among them.
gWhiz has mobile apps under its Prepzilla brand that allows students to practice alone or with a friend online. I plan to assign this for my high school math/calc students as homework and practice alternatives this year since it seems to be available on multiple devices and free download.
Piazza (https://piazza.com/) looks pretty good and is free, but I haven't tried it at the HS level yet.