What if you were given a picture of a figure or object, like a map with cities and roads marked on it? How could you explain that picture geometrically? After completing this Concept, you'll be able to describe such a map using geometric terms.

Teacher and Student versions of full lesson from engageNY

Students develop the definition of circle using diameter and radius.

Students know that the distance around a circle is called the circumference and discover that the ratio of the circumference to the diameter of a circle is a special number called pi, written ?.

Students know the formula for the circumference C of a circle of diameter d and radius r. They use scale models to derive these formulas.

Students use 22/7 and 3.14 as estimates for ? and informally show that ? is slightly greater than 3.

Know precise definitions of angle, circle, perpendicular line, parallel line, and line segment, based on the undefined notions of point, line, distance along a line, and distance around a circular arc.

Exercises from Illustrative Mathematics A set of 2 exercises, commentary, and solutions