CCSS.Math.Content.2.NBT.A.1a
The standard
100 can be thought of as a bundle of ten tens — called a "hundred."
Common Core State Standards for Mathematics
What this standard means
Students need to understand that ten groups of ten make one hundred. They should connect 100 to a flat, a bundle, a drawing, a number word, and the numeral 100. The point is not counting to 100 by ones. It is seeing 100 as one larger unit made from ten tens.
Mastery looks like a student saying, “I have ten tens, so I have one hundred,” and showing it with blocks, drawings, or bundles. Common stuck points are counting every single object, mixing up tens and hundreds, or thinking 100 is just three digits instead of a unit.
Ways to teach it
- Have students trade ten ten-sticks for one hundred flat using base-ten blocks, then draw the trade in their math journal.
- Ask, “How is 100 the same as ten tens, and how is it different from ten ones?”
- Show a picture of base-ten blocks and ask students to circle ten tens that make one hundred.
- Connect to money by showing ten dimes and asking why they have the same value as one dollar.
Plan a lesson for CCSS.Math.Content.2.NBT.A.1a
Generate a complete lesson plan aligned to this standard, with objectives, activities, and materials. Free, no account needed.
Related standards
- CCSS.Math.Content.1.NBT.B.2a
10 can be thought of as a bundle of ten ones — called a "ten."
- CCSS.Math.Content.K.CC.A.1
Count to 100 by ones and by tens.
- CCSS.Math.Content.2.NBT.A.1b
The numbers 100, 200, 300, 400, 500, 600, 700, 800, 900 refer to one, two, three, four, five, six, seven, eight, or nine hundreds (and 0 tens and 0 ones).
- CCSS.Math.Content.1.NBT.B.2c
The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).