When the cat’s away the mice will play, but a least you’ll know when they came home if you use this time clock. It’s called the Kid-e-log and [John Boxall] developed it to help a friend who wanted to keep track of their teenage children’s after school activities while they were still at work. He figured having them punch a time clock would at least let you know if they came straight home as they were supposed to. An RFID tag was issued to each (no, they didn’t implant the tags) and used to record the time. To keep fraud to a minimum the hardware has a battery back-up for its real-time clock, and the tag read events are stored to EEPROM for retention between power cycles. This doesn’t prevent common tricks like taking the reader with you, or sending your tag with a sibling, but it’s a start. See it in action after the break.