The Astro Pi board is a Raspberry Pi HAT and will comprise the following:

• Gyroscope, accelerometer and magnetometer sensor
• Temperature sensor
• Barometric pressure sensor
• Humidity sensor
• Real time clock with backup battery
• 8×8 RGB LED display
• Several push buttons

It will also be equipped with both camera module and an infra-red camera.

via Astro Pi – What Can A Raspberry Pi Do In Space?.

During his mission Tim Peake will deploy the Astro Pis, upload the winning code whilst in orbit, set them running, collect the data generated and then download it to be distributed to the winning teams.