2.7 Adding and Subtracting within 1,000

Unit Goals

  • Students use place value understanding, the relationship between addition and subtraction, and properties of operations to add and subtract within 1,000.

Section A Goals

  • Add and subtract numbers within 1,000 without composition or decomposition, and use strategies based on the relationship between addition and subtraction and the properties of operations.

Section B Goals

  • Add numbers within 1,000 using strategies based on place value understanding, including composing a ten or hundred.

Section C Goals

  • Subtract numbers within 1,000 using strategies based on place value understanding, including decomposing a ten or hundred.
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Glossary Entries

  • a third

    One piece of a shape split into 3 pieces that are the same size.

    A third of the rectangle is shaded.

  • bar graph
    A way to show how many in each group or category using the length of rectangles.
  • centimeter

    A length unit in the metric measurement system. There are 100 centimeters in a meter.

  • compose
    To make a new unit from 10 of the next smallest unit. For example, compose a ten from 10 ones.
  • 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.
  • decompose
    To break a unit into 10 of the next smallest unit.  For example, decompose a ten into 10 ones.
  • expanded form

    A specific way of writing a number as a sum of hundreds, tens, and ones.

    Expanded form writes a number as a sum of the value of each digit. Example: 482 written in expanded form is \(400 + 80 + 2\) .

  • face
    A flat side of a solid shape.
  • foot

    A length unit in the U.S. customary measurement system.

    There are 12 inches in a foot.

  • hexagon

    A shape with 6 sides and 6 corners.

  • inch

    A length unit in the U.S. customary measurement system. 

    There are 12 inches in a foot.

  • line plot
    A way to show how many of each measurement using an x for each measurement.
  • meter

    A length unit in the metric measurement system. 

    There are 100 centimeters in a meter.

  • number line

    A diagram that represents numbers as lengths from 0 using equally spaced tick marks or points.

  • pentagon
    A shape with 5 sides and 5 corners.
  • picture graph
    A way to show how many in each group or category using pictures of the objects or symbols.
  • quadrilateral
    A shape with 4 sides and 4 corners.
  • thirds

    The pieces created when a shape is split into 3 pieces that are the same size.

    This circle is split into thirds.