Here are some challenges you can use as models for the first couple of days with robotics. I've used versions of these challenges with young children all the way to adults. They help to introduce the different aspects of robotics from simple moves to responding to sensors and looping. Use these ideas as a start for your own class or to start you on your robotic journey. Modify this as you wish!
Nothing will stop your robotic projects faster than technology problems. Here is a cheat-sheet of common problems and resolutions. Notice the last row is blank. This was for instructions on how to clear the memory on the NXT vs the EV3 depending on the equipment the school had.