You might like to experiment with the code for the projects in this lesson. You could for example make both the magnet detector and accelerometer project more sensitive. You could change the magnet detector project so that it counted the number of times a magnet was brought close to it. This technique of a magnet and magnetic sensor can be used to count the rotations of a wheel.
If you have found this lesson useful, and want to learn Python, then you might like my book Programming the BBC micro:bit: Getting Started with MicroPython.