If you are modifying a drawing, use dotted lines or colored chalk. If you make a mistake, the same rule applies. Correct the mistake with additional notations and explain the mistake but leave the original in place so that your students can follow the corrections. Give students time to copy chalkboard material into their notes before asking them to comment and before moving on to a new topic. Do Not Doodle.
Students rightly assume that what is on the board is important.
Use the chalkboard to highlight and emphasize. Put no insignificant information on the board. Check with Your Students. Occasionally check with your students to make sure that they can see the material on the chalkboard. As part of your class planning, decide what material you will put on the board.