Recorders are used in many places as an introductory musical instrument because of its easy playability and construction. Recorders produce a flute-like sound when the player blows into the mouthpiece. When a note hole is completely covered, the pitch is fixed, meaning it has a definite tone that does not shift. When a recorder needs to be tuned, the mouthpiece must be adjusted or changes to the finger position over the note holes must be shifted.
Hold the recorder as if it were being played, and cover the second hole with your left hand's middle finger. This is a C note. Blow a steady stream of air to produce a pitch, and check the pitch with the tuner.
Adjust the recorder itself to fix any intonation. If the pitch played is sharp, slide the mouthpiece out slightly to flatten the pitch. If the note is flat, push the recorder in, if possible, to raise the pitch.
Make any further adjustments by changing finger placement. Sliding fingers off the finger holes so they are slightly open will further help any pitch problems. Mouth positioning can also help pitch. Dropping the jaw will flatten the pitch, and compressing the jaw and constricting airspace will raise the pitch.