Math Games

Grade 2 - Number

Standard 2.N.10 - Simplify both sides of the equation and find the missing number that makes the equation true.

Included Skills:

Apply mental mathematics strategies for basic addition facts and related subtraction facts to 18.
• Explain or demonstrate the mental mathematics strategy that could be used to determine a basic fact, such as:
- doubles; e.g., for 4 + 6, think 5 + 5.
- doubles plus one; e.g., for 4 + 5, think 4 + 4 + 1.
- doubles take away one; e.g., for 4 + 5, think 5 + 5 – 1.
- doubles plus two; e.g., for 4 + 6, think 4 + 4 + 2.
- doubles take away two; e.g., for 4 + 6, think 6 + 6 – 2.
- making 10; e.g., for 7 + 5, think 7 + 3 + 2.
- one more; e.g., for 7 + 1, think one more than 7.
- one less; e.g., for 9 – 1, think one less than 9.
- two more; e.g., for 6 + 2, think two more than 6.
- two less; e.g., for 11 – 2, think two less than 11.
- building on a known double; e.g., 6 + 6 = 12, so 6 + 7 = 12 + 1 = 13.
- addition for subtraction; e.g., for 7 – 3, think 3 + ? = 7.
• Use and describe a mental mathematics strategy for determining a sum to 18 and the related subtraction facts.
• Refine mental mathematics strategies to increase their efficiency.
• Demonstrate understanding and application of strategies for addition facts up to and including 9 + 9 and related subtraction facts.
• Demonstrate recall/memorization of addition facts up to and including 5 + 5 and related subtraction facts.