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Comparing Three-Digit Numbers
Students will be able to compare two three-digit numbers at a time using the >, <, or = signs to record their answers.
- Give students a short number comparison problem to introduce them to the lesson. For example: My brother and I went bowling over the weekend. I scored 105 points and he scored 131 points.
- Ask your students who won and have them explain their answers.
- Tell students that today they will be learning how to compare three-digit numbers by using <,>, or = to show their answers.
Explicit instruction/Teacher modeling(5 minutes)
- Referring back to the above example, share with students how you would write this comparison. Tell them that you would write "105 < 131" because 105 is less than 131. Tell students that you know this because when you compared the hundreds value of both numbers, they were equal.
- You then moved on to comparing the numbers in the tens place, and found your brother's number to be larger. Tell students how you would prove this same finding on a number line.
- Draw a number line labeled 100 to 200 with intervals of 10 on the board. Draw a star approximately where 105 and 131 would fall on the number line. Ask your students how this shows that 105 is less than 131.
Guided practice/Interactive modeling(15 minutes)
- Project number lines on the board.
- Give students a another short word problem: Sam got $185 for his birthday and Sarah got $149. Who got more money for their birthday?
- Place each number on the number line. You can make a star or dot where each number should go on the number line.
- Tell your students to check which number is closer to 100, or closer to the left, because 100 is the smallest number on this number line.
- Ask your students who got less money for their birthday? Have them explain.
- Show students how to write the comparisons sentence on the blank lines. Your answer should look like "185 > 149."
- Ask your students to justify this answer.
- Give students two numbers, 330 and 705, and ask them to use the number line to compare them. Advise students to number the dash marks on the number line before completing the problem.
- Have students work in pairs to complete this task.
- Ask a group to come up to the board and explain to the class how they labeled the number line, where they put the points, and what symbol they included in their final answer. Ask another group to either explain why they agree or disagree with the first group's answer.
Independent working time(10 minutes)
- Give students the number pairs 250 and 295 and 784 and 725 to compare.
- Have students use the number lines to compare these numbers on their own.
- Remind students to label their number line first, then add the points, and then write the correct comparison symbol.
- Enrichment: Students who need an extra challenge may be given three three-digit numbers and be asked to put them in order after they finish their independent work.
- Support: Students struggling with the symbols may need the crocodile mouth explained and the teeth drawn in on the symbols. Remember, the mouth is always open to the greater number. Alternatively, students may need a partner to work with them throughout the whole activity if this is the first time they are being exposed to comparing three-digit numbers.
- Give each student a sticky note.
- Have them complete the following comparisons on the sticky note: 110 ____ 165 and 456 ____ 345
Review and closing(5 minutes)
- Give students a scale to help them self assess their understanding of this lesson.
- 3: You could teach someone else how to plot points on a number line and write the correct comparison symbol.
- 2: Most of the time you feel like you could plot points on a number line and write the correct comparison symbol.
- 1: You are still pretty confused about how to plot points on a number line and write the correct comparison symbol.
- Ask students to give a final summary of the lesson. Remind them to include plotting points on a number line, figuring out which number is greater, and which each of the comparison symbols represent.