This Instructional Activity is a part of the Lesson 19, Unit 5, Grade 7. Prior to the start of the lesson, prepare the following: A bag containing cubes (or beads or slips of paper, etc.) for each group of four students. Forty should be red, and the remaining cubes can be any other color. On the board, draw a number line similar to the one shown below. Today we are going to learn something about the population of cubes in this bag.