Understanding Place Value

Introduction

• Write the number 159 on the whiteboard. Pass out personal whiteboards and whiteboard markers to each student. Provide students with access to base-ten blocks (enough for each student to create the number 159).
• Say, "I want you to think about which digit in this number is worth the most in the number, and which digit is worth the least in this number. I'm not going to explain what these words mean yet, I want to see what you already know!"
• Allow the students a few minutes to solve the problem. Rotate around the room and ask students to explain their thinking to you. If a student is confused and doesn't know where to start, support them by reminding them that each digit is in a different place value (e.g. 9 ones, 5 tens, 1 hundred). Don't give students the correct answer, instead, gently guide them as they think about the question.
• Put students in partnerships and have students first identify what is similar and what is different about their approaches to solving the problem. This can also be an initial discussion about what worked well in this or that approach, and what might make this or that approach more complete or easy to understand.
• Provide a sentence frame to support students in discussing their ideas, and ask a partnership to model reading and completing the sentence frame in front of the rest of the students. An example sentence frame is:
  • The digit that is worth the most is ________. I know this because ________.
  • The digit that is worth the least is ________. I know this because ________.
  • My partner and I both used ________ to solve the problem.
  • I used ________ to solve the problem, but my partner used ________ instead.
• Allow the students a few minutes to discuss the similarities and differences of their approaches.