Playing high notes is a matter of confidence; firstly, confidence in one's instrument, that it can play the notes in the second register, and secondly, confidence in oneself, that one has the ability to produce these notes at will. On a suitable recorder high notes are not difficult and in the lessons themselves you have already played them as individual notes and in the tunes where they were introduced. This exercise offers high notes in scales and also in arpeggiation, the latter generally more difficult than the former. Play this exercise slowly until you feel confident that you are reading the notes accurately. Only once this has been achieved should you take the exercise at a faster speed. Make sure the highest notes, the B, C and D remain sweet. They should never sound ugly.