- Second Grade
- 60 minutes
- Standards: 2.NBT.A.3
Students will learn how to find the actual value of three-digit numbers with this activity that has them use manipulatives to create the expanded form of a number.
Students will understand place values of two and three-digit numbers and be able to write the expanded form of given numbers.
Introduction (10 minutes)
- Remind students of what they have already learned about place value. This should include how 2-digit numbers have a ones and a tens place.
- On the board draw a place value chart, and in it write a two-digit number.
- Using base ten blocks, show your students this number.
- Use craft sticks to count the students in the class. For example, If you have 24 students you should also have 24 craft sticks.
- Count out groups of 10 sticks, wrapping each group with a rubber band.
- Have your students count the number of groups. Remind them that there are ten sticks in each of those groups, so even if they counted two groups, that means there are 20 sticks total.
- Use ten frames to represent the same number.
- Using linking cubes to represent this same number again.
Explicit Instruction/Teacher Modeling (15 minutes)
- Model another two-digit number using any of the above methods.
- Once your students seem to have a grasp on these representations, use the base ten blocks to model a three-digit number.
- Talk about how you are modeling the number, including what the different kinds of blocks represent, and write the number out in expanded form.
- After that choose a few more numbers to model for the students.
- Explain to students that expanded numbers show the value on each digit individually.
- Write an example number in expanded form to show students this technique. Example: 300+20+1
Guided Practice/Interactive Modeling (15 minutes)
- Have two bins containing the linking cubes and the base ten blocks set out our for each group.
- Ask the students to work together to make numbers you will give them.
- Write a few numbers on the board for your groups to work on.
- Ask your students to write down the expanded form of the given numbers on a separate piece of paper.
Independent Working Time (10 minutes)
- Tell students that they are now going to do the same thing, but individually.
- Put up several numbers on the board and have students use the base ten blocks or linking cubes to represent the numbers and then have them write the number's expanded form on a piece of paper.
- Enrichment: Let advanced students use base ten blocks to try to find the expanded form of four-digit numbers.
- Support: Give struggling students one-on-one assistance. Pair struggling students with peer mentors.
Assessment (5 minutes)
- Throughout the lesson, make notes about your students to determine whether or not they understand the material.
Review and Closing (5 minutes)
- Review the fact that two and three-digit numbers contain different place values.
- Draw a place value chart to demonstrate your point with a two-digit number, then with a couple of three-digit numbers.