An interactive clock.
The time is displayed in four ways - an analog clock, a digital clock, in text, and a representative image of the sky in the background. Hopefully it will help make teaching the time more interesting.
How to use
Obviously you can use the plus and minus buttons to set the time, and the other buttons should be self-explanatory.
Each clock also has two modes - tap the appropriate clock face to toggle them. The analog clock can show the value of the minute hand at each hour; the digital clock can show the time in AM/PM or 24-hour modes; and the text clock can use simple or verbose language.