During Unit 3, your children will use numbers to 20, including written numerals, to represent quantities and to solve quantitative problems, such as counting objects in a set; counting out a given number of objects; comparing sets or numerals; and modeling simple joining and separating situations with sets of objects, or eventually with equations such as 5 + 2 = 7 and 7 – 2 = 5.   Students will develop the understanding of groups of ten and leftover ones to form numbers up to 20.

Printable Parent Letter

Key Vocabulary

Your child needs to:

  • Review counting to 100 by ones and tens
  • Review counting forward from a number other than 1
  • Write the numbers 0-20 and represent an amount of object with a written numeral
  • Count up to 20 objects one at a time, giving each object a number name
  • Understand that the last number said names the total amount for a group of objects
  • Understand that each successive number name refers to a quantity that is one larger
  • Count to answer “how many?” questions about as many as 20 things arranged in a line, a rectangular array, or a circle, or a scattered configuration
  • Count out a set of up to 20 objects
  • Review identifying whether the number of objects in a one group is greater than, less than, or equal to the number of objects in another group
  • Review comparing two numbers between 1 and 10 presented as written numerals
  • Compose and decompose numbers from 11 to 19 into tens and ones and further ones. (E.g. use concrete materials to make groups of ten and ones) by using objects or drawings and record each composition or decomposition by a drawing or equation (e.g., 18= 10+8); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.
  • Continue to work towards goal of fluently adding and subtracting within 20 using +1, -1, +0, -0 strategies.