Engineering.com is a brilliant website for all subject and topics related to CDT. They have a Tab at the top of the page for Engineering Games.
Log onto a computer each (or if not possible work in pairs). And have a go at a number of the different games availible.
All games have the black Engineering.com web banner at the top of the page so it should be easy to see if they are playing approved games or if they are on other games websites.
The website also has alot of useful Videos and Resourses so an aditional task could be watched or completed. Try and find something related to whatever topic you are currently working on in class.