This Application Problem is a part of the Lesson 9, Unit 4, Grade 4. This Application Problem reviews measuring, constructing, verifying with a protractor, and recognizing in their environment 90 angles as taught in Topic B. List times on the clock in which the angle between the hour and minute hands is 90. Use a student clock, watch, or real clock. Verify your work using a protractor. Stay alert for this misconception: Why don't the hands at 3:30 form a 90 angle as expected?