Strategies to add and subtract within 20

Front

What is addition?

Back

Addition is the process of finding the total or sum by combining two or more numbers.

Front

What is subtraction?

Back

Subtraction is the process of taking one number away from another.

Front

What is a number line?

Back

A number line is a straight line with numbers placed at equal intervals along its length, used to represent numbers and their relationships.

Front

What does it mean to find a missing number?

Back

Finding a missing number means determining a number that, when added or subtracted from another number, results in a specific total.

Front

What is a doubles fact?

Back

A doubles fact is a math fact where a number is added to itself, such as 4 + 4 = 8.

Front

What is the sum of 10 + 5?

Back

The sum of 10 + 5 is 15.

Front

What is the difference in 15 - 2?

Back

The difference in 15 - 2 is 13.

Front

What is a number sentence?

Back

A number sentence is a mathematical statement that includes numbers and an operation, such as addition or subtraction.

Front

What does it mean to solve a number sentence?

Back

To solve a number sentence means to find the answer or result of the mathematical operation.

Front

What is the relationship between addition and subtraction?

Back

Addition and subtraction are inverse operations; if you add a number and then subtract the same number, you return to the original number.