It is to be hoped that you have a recorder to hand (the lesson requires you to make use of it for a practical demonstration), that your instrument is undamaged, and that you are in good health (at least able to breathe normally).
It is important to note that recorders are easily damaged ; the slightest roughening of the central bore of the instrument, and much more importantly, of the windway between the embouchure and the windcutter will adversely affect the sound of the instrument, and in extreme cases, prevent it from speaking altogether.
Most people say that the recorder is a blown instrument, this is an exaggeration however. Little more than a normal breath is quite sufficient to make it sing. Following the fingering chart below, to demonstrate the amount of breath required, take a deep breath, put the instrument to your lips, and let your breath out freely as if you were sighing.
Red fingerholes are closed. Black fingerholes are open.
The result will be a horrendous screeching as the instrument is overblown, followed by a more normal tone as the air pressure decreases, and finally warbling as the pressure falls completely beyond the point at which the instrument will sing.
With the instrument to your lips, using your left hand, close the thumbhole (bottom) and 1st, 2nd and 3rd holes at the top of the instrument. Support the instrument with your right thumb. Practice blowing gently until you achieve the most satisfying tone.
Once you can achieve a pleasant tone, practice the same exercise with the 4th, 5th, 6th and 7th holes (the 6th and 7th are usually pairs of small holes which should both be closed for this excercise). The 6th and 7th holes will probably be the most difficult to produce a pleasing tone. Don't become discouraged, keep experimenting until you are happy with the result.
Problems when playing edit
It is not unusual to experience problems with the recorder gradually becoming more difficult to play during a session (particularly if the surrounding air is cold) owing to buildup of condensation within the windway. To determine if this is the case, sight along the windway from the embouchure to see whether there are any globules of moisture blocking the passage.
Opinions on the best way to clear moisture from the windway vary from player to player; my own recommendation is to suck air through the embouchure. The moisture is only condensed water from your warm breath and presents no health hazard.
The surface of the windcutter should always be treated with the utmost care! While it may be acceptable to place a finger lightly over the window of the head joint and blow to clear moisture in a plastic recorder, if the same method is applied to a wooden recorder it will gradually warp the windcutter.
If it is ever necessary to remove an obstacle from the windway, use nothing harder than a downy feather carefully inserted from the embouchure.