This system is designed for use on an interactive whiteboard. Each child in the class chooses an avatar and then the teacher can add or take away points based on certain criteria. The reasons for adding/subtracting points can be customised so, for example, you could award a point to Pupil X and it would say "1 point earned for being mannerly." You can clear the counters so it's back to zero when you please so it's ideal for daily/weekly/monthly targets.
The author of the review, Nigel Lane made a video walkthrough of the main features of ClassDojo. I've posted it below for your viewing pleasure!
Click here to read the full review.
Click here to visit the ClassDojo site.