Making your own lab equipment is fun!
Electrical energy is crucial in our lives, and it is very important to know how we use it in order to be aware of how to do it prudently.
Arduino based ohm metre will help to know unknown resistor values
Using ATtiny24's capable ADC, this probe can measure voltages from 1mV to 20V and currents from ~1mA to 2Amps with reasonable accuracy.