This Instructional Activity is a part of the Lesson 17, Unit 2, Grade 6. Discuss students' results from the Opening Exercise. Have students share their answers, or the teacher can conduct a poll (raising hands, standing up, electronically) to determine where students placed each number. After sharing which numbers belong in each circle, have students examine the numbers in the Opening Exercise. Ask students to find rules to determine in which group the number belongs just by looking at it. Ask students to discuss the divisibility rules for each number, and have them take notes in their materials.