My students love the time tracker. It's a great tool to keep track of and be aware of time. I would advice getting the adapter, to avoid using batteries.

Kids have enough adults pestering them to keep up with timing on practicing, how long they have been working on a project, etc. This is just a way to eliminate the need for grown-ups to monitor kids -- it gives them a sense of responsibility. As the lights begin to flash, it also gives them a sense that it isn't going to last forever!