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    • ▾1st grade
      • ▾Place value
        • •Count and write numbers within 120
        • •Skip count by 3s and 4s
        • •Place value with tens
        • •Compare two-digit numbers
      • ▸Addition and subtraction
        • •River crossing puzzles
        • •Add and subtract within 20
        • •Add within 20, word problems involving three addends
        • •Use one addition problem to solve another
        • •Add by making tens
        • •Subtract by adding
        • •Understand the equals sign
        • •Add and subtract within 20, missing number problems
        • •Add and subtract within 20, word problems
        • •Add within 100, concrete and pictorial
        • •10 more or 10 less
        • •Subtract multiples of ten from multiples of ten
      • ▸Measurement, data, and geometry
        • •Order without tools
        • •Measure given a unit
        • •Bar and picture graphs having three categories of data
        • •Tell and write time, hour and half-hours
        • •Definitions of shapes
        • •Compose 2D and 3D shapes
        • •Halves and quarters
     › 1st grade › Place value

    Place value with tens

    Understand place value with units and tens. Represent numbers 0-99 with place value blocks. For example, given the number 72, the student should choose 7 ten blocks and 2 unit blocks. Working the other way, given 3 ten blocks and 1 unit block, the student should deduce 31.

    Watch these Khan Academy videos:

    • Intro to place value
    • Place value example: 25
    • Place value example: 42

    Do these Khan Academy exercises:

    • Groups of ten objects
    • Tens and ones
    • 2-digit place value challenge

    Conclude by leading this investigation:

    Building Skyscrapers of Different Heights
    by MathPickle

    1.NBT.B.2: Understand that the two digits of a two-digit number represent amounts of tens and ones.

    Additional lessons and practice problems