In this unit students • find all decompositions of 10 and write them using equations; • represent a number between 11 and 19 as a bundle of ten and some ones; • take a first pass at adding one-digit numbers whose sum is greater than 10.
The units are structured so students build their understanding of place value in order to add and subtract larger numbers. This unit focuses on making ten, a foundational idea for the understanding of place value. Students learn that 10 ones bundle to become a “ten.” They find all decompositions of 10 and represent them with equations. They build on that idea by adding ones to a ten in order to compose the numbers 11–19. Knowing that each digit in a two-digit number represents a value that is not the same even if the numeral is the same is important foundational work for developing a strong number sense. Students also work on counting (making progress towards counting to 120) and reading and writing numerals. This work supports students developing fluency with adding and subtracting within 10. They answer questions like “How many more to make 10?” and physically bundle objects in groups of 10. The number line supports all of this work.
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