## Lesson: Compare Whole Numbers to 100 Developing the Concept

Materials: number line and number cards 0 – 20; base-ten blocks (tens rods and ones units) or beans and bean sticks; overhead projector and overhead base-ten blocks, if available

Preparation: Put a number line on the board or on the floor. Prepare a large card for each symbol > and <.

Prerequisite Skills and Concepts: Children should be able to count and write numbers 0 – 10 and should be familiar with ordering numbers 0 – 10.

• Say: Yesterday we talked about numbers that are greater than or less than other numbers. Today we are going to use a number line to help find the numbers.
• Ask: Would someone come up and choose a number and put it where it belongs on the number line? How did you know where to put it?
Elicit from the child that he/she looked at the number, at the number line, and then counted up (or back) to find where to place it. Then have another child choose another number.
• Ask: Is this number greater than or less than the first number? How do you know?
Elicit from children the correct answer and whether it comes before, and is less than the first number, or comes after, and is greater than the first number.
• Continue this activity until children have an understanding of greater than and less than. Then introduce using beans and bean sticks or base-ten blocks to work with numbers to 20.
• Say: Now let's try comparing numbers that are greater than and less than by using tens and ones base-ten blocks (or beans and bean sticks).
Discuss with children the value of each manipulative. Have children line up ten blocks (or beans) beside the tens rod (or bean stick)
• Ask: How many ones are in the tens rod?
Elicit that there are 10.
• Say: Show me how to make 7. Save that. Now show me how to make 12.
• Check children's work. If you have an overhead, use rods and units to show the children both numbers.
• Ask: Which number is greater than the other number? (12) How do you know?
Children should say the number with 1 ten is greater than the number without any ten.
• Say: Now make the numbers 11 and 16 with base-ten blocks.
• Ask: Which number is less than the other number? (11) How do you know?
Children should say that both numbers have 1 ten, but eleven has only 1 one and 16 has 6 ones. The number with fewer ones is less.
• Say: Now make the numbers 10 and 20 with base-ten blocks.
• Ask: Which number is greater than the other number? (20) How do you know?
Children should say that both numbers have tens, but no ones, and that 10 has 1 ten and 20 has 2 tens, so 20 is larger.
• Ask: How do you know when a number is greater than another number?
Children should say that if one number has more tens, that number is greater. If both numbers have the same number of tens, and one number has more ones, that number is greater.
• Finally, introduce the symbols > and <. Write 5 > 2 and 3 < 9 on the board. Show children how the large opening of each sign is closest to the greater number, and the small, pointy end of both signs points to the smaller, or lesser number. Allow time for volunteers to come to the board and replace the numbers with other numbers, making sure that the numbers are placed correctly. Then have children use large number cards and the large > and < symbol cards to act out comparing numbers with the symbols.
• Once children have become proficient in comparing numbers 0 – 20, use these activities with greater numbers.

Wrap-Up and Assessment Hints
There is a lot of material covered in this unit, and the different skills need lots of practice. As you wrap up, reinforce the vocabulary, making certain the children have a thorough understanding of the concepts presented. Make sure that children are proficient in one set of numbers before introducing larger numbers.