Free worksheets on fact family traingles / number triangles dealing with numbers up to 20 for 1st grade elementary math.
Fact family triangles can all be sovled by using the same principle. In the triangle, you can find on the right-hand side, the sum of the two numbers that are in the adjacent boxes of the triangle. Either addition or subtraction must be used to complete the triangle. Students can recognize which operations to use based off of what is already filled in. Students can also find unfilled number triangles to print. Encourage the children to make their own number triangles with various difficulties. The tasks without going past the tens place are going to be useful later on, so it is important to repeat these simple tasks until the children no longer have any difficulties.