I just stumbled across this website. It lists all the questions in the Canadian PSTAR exam and gives the answers as well as explanations of each answer. There is huge overlap between these questions and those on the Ultra-light exam. You should pass this along to your students they will likely find it helpful when studying. I wish I’d seen this 2 weeks ago!
Your students who are android users will also probably like the GPS app and associated website I mentioned before too.
Their website is: http://www.ppgps.info/PPGpS.aspx