For exercise 4, using the board look at all of the squares controlled by:
– the f1-bishop developed to e2 (place only this bishop on the board)
– the f1-bishop developed to d3, c4, b5
– the f8-bishop developed on e7, d6, c5, b4
– all remaining bishops as above
Then, without the use of the board repeat the exercise again visualizing the squares controlled by the bishops above.
Perform this exercise for 2 sessions or until you feel comfortable.