The importance of legibility cannot be overemphasised. The noise level will rise if students have to consult their neighbours about blackboard notes which are written too small or handouts which are not projected clearly. On blackboards, the thick white chalk is by far the most easily visible. Orange and yellow chalk are the only other colours visible at the back of the lecture theatres, but it is not easy to distinguish between them so do not use both. Labelling diagrams in other colours is unhelpful.
Red ink is difficult to see.
Please make sure that the image projected by the OHPs is fully visible, and is not projected onto the top of the blackboards or above the projection screen. Lecturers should never tolerate talking at the back of the lecture room as this is distracting for other students who are trying to concentrate. Some courses rely heavily on a single source book. Such a single source book can also be used adversely to cram in too much material for the time allocated. Often other books are as helpful and interesting, and should also be recommended.