I am working on a school project that includes both my raspberry pi and aruduino, I have made a temperature script that allows me to monitor the pi's current temperature and I am wondering if I can read this output from my arduino in order to control a fan's speed.
You can actually to it all with the Raspberry Pi. Control you fan with a PWM value that will then turn on and off a MOSFET.
If you really have to do it with the Arduino, the "simple noob" way of doing this is to send a PWM pulse output from the Pi and analog read it from the Arduino. From there, do the same as you would do with the Pi.
How to read raspberry pi temperature from script on an Arduino to control fan