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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 › Addition and subtraction

    Add within 100, concrete and pictorial

    Students will learn how to add within 100, with and without regrouping, using base ten blocks, place value disks, and number lines. Make sure to include problems where exchanging for a ten is necessary. Students will also learn how to add multiples of ten using a hundreds chart. For example, 20 + 30 = ? Here's a lesson on that.

    Addition and subtraction with number lines by Khan Academy

    Add within 100 using a number line by Khan Academy

    Next, give your students this challenge:

    2018 Math Kangaroo Levels 1-2 Problem #17 by STEM4all

    Conclude by leading this investigation:

    Number Icicles
    by MathPickle

    1.NBT.C.4: Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used. Understand that in adding two-digit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten.

    Lessons and practice problems