Google Science Journal is a neat app I’ve been playing with. The name is misleading. It’s really a collection of “devices”–using your phone’s sensors to measure light intensity, sound, and acceleration in three planes. It also records and graphs data from those sensors and allows you to make notes on the conditions in which you took the data. Best of all, it’s COPPA compliant, so it doesn’t collect data on your students or show them ads–this is what raises it above other apps you could use to get these functions on a smart phone.
For more information and a (long, fun-looking) list of possible activities, look here. To download the app, look up “science journal” on the Play store.
(look for this image to know you have the right app)