1.4 Numbers to 99

Unit Goals

  • Students develop an understanding of place value for numbers up to 99.

Section A Goals

  • Add and subtract multiples of 10.
  • Represent the base-ten structure of multiples of 10 up to 90 using towers of 10, drawings, numbers, or words.

Section B Goals

  • Add and subtract multiples of 10.
  • Represent the base-ten structure of numbers up to 99 using drawings, numbers, and words.
  • Understand that the two digits of a two-digit number represent amounts of tens and ones.

Section C Goals

  • Compare 2 two-digit numbers based on the values of the tens and ones digits, recording the results of comparisons with the symbols >, =, and <.

Section D Goals

  • Represent two-digit numbers in different ways, using different amounts of tens and ones.
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Glossary Entries

  • category
    A label that tells how objects in a group are alike.
  • data
    Information about the things or people in a group.

    Example: If you have a box of colored pencils, then the lengths and colors of each of the pencils are data about the pencils in the box.
  • difference
    The result when one number is subtracted from another.
  • estimate

    To find a value that is close to the correct value.

  • greater than

    63 is greater than 32.
    63 > 32

  • less than

    32 is less than 63.
    32 < 63

  • sum
    The total when two or more numbers are added.
  • survey
    A way to collect data using a group of people answering the same question.
  • teen number

    A number with 1 ten and between 1 and 9 ones.

    Example:
    Fifteen is 1 ten and 5 ones.

  • two-digit number