Learning goals: Teacher Facing Compare (orally) different ways to measure a circle, and generalize the relationship between radius and diameter. Comprehend the terms “diameter,” “center,” “radius,” and “circumference” in reference to parts of a circle. Describe (orally and in writing) the defining characteristics of a circle. Full lesson plan (warm-up, activities, synthesis, cool-down prompt) from 7.3 Measuring Circles, Grade 7.