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Number Concepts to 20

5 min readGrade 1 · Number

Numbers to 20 build directly on Kindergarten foundations. The key conceptual leap is base 10: 13 is not just a symbol but one group of ten and three more. Double ten-frames make this structure visible. Students who truly understand ten-and-some-more are equipped for place value, addition, and subtraction across the curriculum.

Ten and some more

Numbers 11-20 are the first encounter with base 10 structure. 14 is 10 and 4 more; 17 is 10 and 7 more. A double ten-frame makes this concrete: the left frame is always full (10) and the right frame shows the extra. Students who see 16 as one full frame and 6 have the foundation for column addition and place value.

Counting on and counting back

Counting on is the first major efficiency gain: instead of counting from 1, start from the larger number. 8+3 becomes counting 9, 10, 11. This strategy reduces errors and builds mental flexibility. The hundred chart supports both forward and backward counting and reveals skip-counting patterns.

First Peoples counting systems

First Peoples across BC use diverse, sophisticated counting systems. The Tsimshian base-10 system, Tlingit and Kaska counting books, and resources from Native Northwest publishers connect number concepts to place and culture. The BC curriculum specifically recommends these books as counting contexts.

KEY VOCABULARY
Base 10Our number system groups by tens: 10 ones make 1 ten.
Counting onStarting from a known number and counting forward rather than starting from 1.
SubitizeInstantly recognizing a quantity without counting.
Ten-frameA 2x5 grid used to visualize numbers in relation to 5 and 10.