Math Games

Grade 3 - Number

Standard 3.N.10 - Write a subtraction sentence to represent the word problem with numbers up to 18.

Included Skills:

Apply mental mathematics strategies and number properties in order to understand and recall basic addition facts and related subtraction facts to 18.
• Describe a mental mathematics strategy that could be used to determine a given basic fact, such as:
- doubles; e.g., for 6 + 8, think 7 + 7.
- doubles plus one; e.g., for 6 + 7, think 6 + 6 + 1.
- doubles take away one; e.g., for 6 + 7, think 7 + 7 – 1.
- doubles plus two; e.g., for 6 + 8, think 6 + 6 + 2.
- doubles take away two; e.g., for 6 + 8, think 8 + 8 – 2.
- making 10; e.g., for 6 + 8, think 6 + 4 + 4 or 8 + 2 + 4.
- commutative property; e.g., for 3 + 9, think 9 + 3.
- addition for subtraction; e.g., for 13 – 7, think 7 + ? = 13.
• Apply the property of zero to determine a given sum or difference when adding or subtracting zero; e.g., 5 + 0 = 5 and 5 – 0 = 5.
• Provide a rule for determining answers when adding and subtracting zero.
• Apply a mental mathematics strategy to provide a solution to a given basic addition fact up to and including 9 + 9 or a related subtraction fact.
• Demonstrate understanding, recall/memorization and application of addition facts up to and including 9 + 9 and related subtraction facts.