I have attached a zipped instructional guide for using the DS3231 real-time clock with the
micro:bit v2 and micropython v3 development environment. The guide covers many topics
and instructional objectives for beginners including:

• how to layout, create, and use a very simple class structure
• how to use the I2C bus for I2C devices connected to the micro:bit
• how to use a microchip datasheet and communicate with the microchip
• bitwise logical operations and byte and bit manipulation
• binary-coded decimals and two's compliment encoding of byte structures
• memoryview and data manipulation
• how to read and write data bytes to/from microchip registers
• how to exploit the features of the ds3231 RTC

The zipped file is linked below:

DS3231 RTC microbit micropython guide.zip