The potato clock is a popular demonstration and/or project in many science classes. Kids (and adults) are always wowed by the various things that can be ‘powered’ by vegetable matter. It really seems that the potato is acting as a living battery-and best of all, it provokes thoughts beyond what they see and the followup questions always involve ‘why can’t we power up the lights or a car using potatoes?” question. Of course we have to explain that the potato is not truly supplying the power (electrons) but it is in fact metal probes within the potato that sacrifice their electrons for the cause. Nevertheless, the potato (or lemon, cantaloupe, etc) clock is a thoroughly worthwhile way to introduce the relationship between electrical and chemical energy into any class. An upgrade to the timeless standby of yesteryear uses everyone’s favorite form of light, lasers. Using an old laser diode easily harvested from an old cd/dvd player or laser pointer, the Lilikoi laser by Maui maker Ryan is a simple circuit that can generate a brief laser pulse using passion fruit in this case. Passion fruit is a considered a nuisance in Maui, and plucking a few orbs and using them to help generate a laser beam seemed natural to Ryan. You’ll get the gist of what is involved in this project from the link below, and it presents an opportunity to do something different with an old standby in your class. A couple of STEM integration notes here: Use the passion fruit story to bring in the biology of fruit and why it tastes sweet, and how the chemistry of fruit makes it taste that way. You can also bring up invasive or nuisance species as another life science strand. Take note of Ryan’s fruit holders he uses to keep it in place, they can easily be fabbed on a 3D printer for those with that capability.