# Learning Math Facts

› Subtraction & Multiplication

Every kid can succeed at learning math facts. But it takes a teacher who understands how to teach math to make it happen!

Mastering math facts isn't just rote memorization. The term "mastery learning" implies that we have internalized a concept so well that we can manipulate and extend meaning from it.

 Teachers have to give kids strategies that really work, but it takes a long time to become proficient at them.There's a trend (always is in education) right now that we shouldn't expect kids to take timed math tests and put a score on how proficient they are.

There is a fine line between teaching strategies, becoming fluent and expecting automaticity  Fluency in math facts does not mean taking a whole minute to solve a problem that should be mentally calculated in a nano-second.

Fluency is having an arsenal of strategies that are efficient.  Students develop automaticity through practice.

So keep that in mind when teaching children how to work quickly with numbers - the goal is to develop methods that will allow them to proceed in higher-order mathematics without stumbling over the basics.

## Subtraction Math Facts Practice

The foundation of teaching children mathematics is developing number sense.

When students have number sense, they can visualize and manipulate numbers using efficient strategies. These strategies are then applied to problem solving exercises.

If you're looking for addition and subtraction strategies, they're found here.  Below are best strategies for teaching subtraction multiplication facts.

1. Counters

Use any counters, such as poker chips, beans or cubes. For the problem: 7-3, the student gets 7 counters, takes away 3 of them, and then counts the remaining ones to find the difference.

Similar to Joining All in the previous page, this is a simple, straight-forward strategy. Even the youngest students understand the concept of learning math facts with this concrete model.

2. Skip Count Backwards

This is one of the most under-used strategies for learning math facts. Try it with your class. They will probably struggle for the first few (or more) times!

Why? We do not "train their brains," so to speak, to subtract numbers as easily as we add them. By working on skip counting backwards every day with your students, you are training their minds to work with numbers from a different angle.

If you can get your students fluent with counting backwards by 5s, 4s, 9s, 11s,...and you will see the difference it makes in learning subtraction math facts. Singapore Math uses this strategy frequently, and their results speak for themselves.

3. Counting Back and Counting Up

Counting Back works best for subtracting 1,2 or 3. It is simply having the student count backwards (22-2=20). A hundreds chart is helpful for students who lack gestalt imagery with learning math facts.

Counting Up is when the student starts at a lower number and then counts up to the higher number. For example, 15-11. The student starts at 11 and counts up to 15. You are actually introducing the inverse property of addition in elementary mathematics.

4. Use a Ten or Doubles

Once students have been memorizing math facts that make a ten and can solve their doubles, they can start to use those strategies to solve subtraction math facts.

If they know that 7+3=10, then that problem can be used for 10-7 and 10-3. This is also teaching pre-algebraic concepts when the difference is written as "n" and the students must solve for it.

Using doubles means that you can use addition doubles to learn subtraction "half-doubles." If 6+6=12, then 13-7=6 since 7 is just one more than 6.

## Multiplication Math Facts Practice

Strategies for teaching math facts for multiplication are quite similar to math addition facts. As always, looking for patterns is the focus of any good strategy we use in teaching basic math facts.

1. Skip Counting

When children skip count, they are informally using multiplication. This is a great strategy to practice math facts as it embeds a pattern into their brains and wets the premise for making groups of things.

When we say 5x3, that really means 5 groups of 3. Skip count by 3: 3, 6, 9, 12, 15. Fifteen is the product.

Use a Hundreds Chart for teaching math facts with skip counting. The students should place a chip or token over every number you skip count by to represent the groups that are being made.

2. Doubles

2x2, 3x3, 4x4...doubles seem to be easier for many children to grasp. You can also use doubling in another way.

Show the students that doubling can help them practice math facts by breaking down a product into simpler, known products.

For example, 4x5 is twice as much as 2x5. 2x5=10, two 10s equals 20, so the product of 4x5=20.

3. The Sum of Known Products

It is useful in learning math facts to know how to use two related problems to solve a more difficult one.

6x8=48 can be challenging. However, since 6x6=36 (doubles!) and 2x6=12 (skip counting!), you can add the two products together to get 6x8=48.

4. Patterns in Numbers

• 0 times anything equals 0
• 1 times a number equals the number itself
• 2 times a number is a double
• 5 times a number always ends in 0 or 5
1. Even numbers times 5 end in 0
2. Odd numbers times 5 end in 5
• 10 times a number always ends in 0
• The Nines: The sum of the digits must equal 9, up to 9x9. Seven times nine? 63 (6+3=9)