2.7.B

Math2nd Grade

The Standard

use an understanding of place value to determine the number that is 10 or 100 more or less than a given number up to 1,200

Texas Essential Knowledge and Skills for Mathematics

Teacher's field guide

What This Standard Means

What Students Need to Do

Students use place value to change a number by one ten or one hundred. They track how the tens, hundreds, or thousands places change when crossing a place-value boundary.

What Mastery Looks Like

Students answer accurately, including when a change crosses into a new hundred or thousand. They can explain which place changed and why the other places stayed the same.

Common Misconceptions

Students may change the wrong digit or change every digit. They may also reverse more and less or miss place-value changes across boundaries, such as finding 10 more than 396.

How to Assess It

Give this exit ticket: “Start with 398. Write the numbers that are 10 more, 10 less, 100 more, and 100 less. Explain one answer.”

Lesson moves

Ways to Teach It

  1. Build 486 with base-ten blocks, add or remove one ten or hundred, then record each new number.

  2. Ask students to explain why 10 more than 795 is 805 instead of 705.

  3. Play a card game where students draw a number, spin 10 or 100 more or less, and state the result.

  4. Use a library count of 735 books, then find the new totals after receiving 100 books or removing 10 books.

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