Effective Subtraction Strategies for Mental Math

Effective Subtraction Strategies for Mental Math

Learning Objectives

At the end of the lesson you will be able to identify and apply various mental math subtraction strategies.
At the end of the lesson you will understand the importance of mastering each strategy in isolation before integrating them.
At the end of the lesson you will be able to use mathematical language accurately while discussing subtraction.
At the end of the lesson you will be capable of choosing the most effective or efficient strategy for different subtraction problems.

What do you already know about mental math subtraction strategies?

Counting Back and Counting Up

Initial subtraction strategies
Teaches counting backwards from the minuend
Teaches counting up from the subtrahend

Thinking Addition

Understanding the inverse relationship between addition and subtraction

Using Doubles and Building on Doubles

Easy recall and near doubles application

Using Ten

Friendly number for easier subtraction computation

Compensation

Adjusting the final answer when dealing with 8s or 9s as subtrahends

Expanding the Subtrahend

Simplifying multi-digit subtraction problems

Mastery of Strategies

Importance of achieving mastery in each strategy before moving to the next

Mathematical Language

Significance of using mathematical language during instruction

Definition List

Minuend: The largest number in a subtraction equation from which the subtrahend is subtracted
Subtrahend: The number being taken away in a subtraction equation
Difference: The result of a subtraction equation
Mastery: The ability to perform a strategy efficiently and confidently without confusion
Mathematical Language: Specific vocabulary used when teaching and discussing mathematics
Effective Strategy: A method that provides the most efficient solution to a problem

Write down 3 things you learned in this lesson.

Have students enter three things they learned in this lesson. With this they can indicate their own learning efficiency of this lesson.

Write down 2 things you want to know more about.

Here, students enter two things they would like to know more about. This not only increases involvement, but also gives them more ownership.

Ask 1 question about something you haven't quite understood yet.

The students indicate here (in question form) with which part of the material they still have difficulty. For the teacher, this not only provides insight into the extent to which the students understand/master the material, but also a good starting point for the next lesson.