An RTC module is an electronic component used to keep track of time. The module usually contains a crystal oscillator that provides a stable and accurate reference frequency. RTC modules usually include a small backup battery that can power the device even when it is off or in the event of a power failure.
The RTC module sensor made by ELECFREAKS can be applied to the microbit in a very user-friendly way, and it is more convenient to use it to realize the recording time teaching case.