I thought that I would share links to a WeBWorK app I heard about in a message from a father who found the WeBWorK app for his son on Google play. He responded directly to a post I made on this forum rather than register to reply in the forum. I'll post the link he sent and another I found on this app.
It did not work for my own server--which is loaded up by the app; everyone's webwork server on the MAA list is loaded. It worked for the person who sent me the info, and the Google play site link above shows screen shots from a session.
2101 14th Street
Cloquet, MN 55720