Learning goals: Teacher Facing Apply circumference and area of circles to calculate the cost of a stained-glass window, and explain (orally and in writing) the solution method. Design a stained-glass window that could be built for a given dollar amount, and present (orally, in writing, and through other representations) a justification that it costs less than the limit. Make simplifying assumptions to solve problems about a stained-glass window. Full lesson plan (warm-up, activities, synthesis, cool-down prompt) from 7.3 Measuring Circles, Grade 7.