This is a basic temperature and humidity sensor which is displayed onto a LCD screen.
The libraries needed are LiquidCrystal and the DHT sensor library by Adafruit.
This project uses the DH11 temperature and humidity sensor. I used an arduino nano but it should work on the uno and mega. There is also a 16 by 2 LCD display, a potentiometer, and a 220 ohm resistor. (Also you might want a breadboard!)