Nick's suggestions are great, and he does this a lot, so listen to him!
I have an alternative suggestion. If your students get on well with Lego robots (EV3, right?) the consider the Arduino Coding Kit. My students (a bit older, but still beginners) really take to the freedom of programming an Arduino after they make a line following color discriminating robot with the EV3s. It gives the students the feeling of going from toy programming to "real" programming.