Subtraction Facts to 20
Key Vocabulary Words: related facts: addition facts and subtraction facts that have the same numbers fact family: a group of related addition and subtraction facts
Doubles Videos:
- use addition and subtraction within 20 to solve word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions (e.g., by using objects, drawings, and equations with a symbol for the unknown number to represent the problem)
- understand subtraction as an unknown-addend problem
- add and subtract within 20, demonstrating fluency for addition and subtraction within 10; use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 - 4 = 13 - 3 - 1 = 10 - 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 - 8 = 4); and creating equivalent bu easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
- determine the unknown whole number in an addition or subtraction equation relating three whole numbers (e.g., 8 + ? = 11, 5 = _ - 3, 6 + 6 = _)
Key Vocabulary Words: related facts: addition facts and subtraction facts that have the same numbers fact family: a group of related addition and subtraction facts
Doubles Videos: