Use the following website to play drones (steady tones) which you can use to practice your intonation (tuning).
http://www.flutopedia.com/reference_drones.htm
- Try matching the pitch exactly.
- Try playing a scale over the root drone (1st note of the scale).
- Try playing a scale over the dominant drone (5th note of the scale).
- Try playing the major 3rd or minor 3rd over a drone of a fifth (1st & 5th notes of the scale).
- Try playing a chromatic scale over any drone.
http://www.flutopedia.com/reference_drones.htm