Exercise 13 Set your turtle up so that pentagon 90 works (the pentagon has 5 sides). Check.

Exercise 14 Try to reproduce this pattern. You will need the new word left. Check.

Exercise 15 A real challenge now - teach the turtle csquare - this stands for "center square" and works like this. You will need two new things:
-- pu means pen up;
-- the turtle "knows" the division sign so :side / 2 means ":side divided by 2".
Check.

Exercise 16 Try to reproduce this pattern. Check.