CCSS.Math.Content.2.NBT.A.1b
The standard
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).
Common Core State Standards for Mathematics
What this standard means
Students need to understand that 100, 200, 300, and so on are groups of hundreds with no tens or ones added. They should connect the spoken number, written number, and base-ten meaning, such as 400 means 4 hundreds, 0 tens, and 0 ones.
Mastery looks like a student reading 700 and saying, “7 hundreds,” then building or drawing 7 hundred flats. Common trouble spots are counting by hundreds without knowing what each number means, or thinking the zeroes are just placeholders with no value connection.
Ways to teach it
- Have students build 100 to 900 with base-ten hundred flats, then label each model with the matching number card.
- Ask students to write: “300 means ___ hundreds, ___ tens, and ___ ones,” then share one example with a partner.
- Show 600 on the board and ask students to hold up fingers for how many hundreds it has.
- Connect to money by showing $100 bills and asking how many bills make $500, $800, and $900.
Plan a lesson for CCSS.Math.Content.2.NBT.A.1b
Generate a complete lesson plan aligned to this standard, with objectives, activities, and materials. Free, no account needed.
Related standards
- CCSS.Math.Content.K.CC.A.1
Count to 100 by ones and by tens.
- CCSS.Math.Content.1.NBT.B.2b
The numbers from 11 to 19 are composed of a ten and one, two, three, four, five, six, seven, eight, or nine ones.
- CCSS.Math.Content.2.NBT.A.1a
100 can be thought of as a bundle of ten tens — called a "hundred."
- 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).