## Wednesday, March 15, 2017

### The Importance of Skip-Counting

Skip-counting is a fundamental math skill which is often not covered by math curriculums.

What is skip-counting? Quite simply, skip-counting is counting by multiples of a number. The following list shows skip-counting by the numbers 2 through 9. In each example, the list could continue on indefinitely.

2: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20
3: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30
4: 4, 8, 12, 16, 20, 24, 28, 32, 36, 40
5: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50
6: 6, 12, 18, 24, 30, 36, 42, 48, 54, 60
7: 7, 14, 21, 28, 35, 42, 49, 56, 63, 70
8: 8, 16, 24, 32, 40, 48, 56, 64, 72, 80
9: 9, 18, 27, 36, 45, 54, 63, 72, 81, 90

If kids begin elementary math with a strong foundation in number sense, which involves skip-counting, it enables them to rapidly absorb higher level math concepts. It is not unreasonable to cover math that is typically taught in grades 3-6 in less than a year. This is because there are lots of math concepts with roots in skip-counting. It takes the majority of math time in grades 3-6 to cover these concepts. Once kids understand and can rapidly skip-count, they can fly through these numerous math concepts.

Not only does skip-counting have benefit because it enables children to rapidly progress through math curriculum. Skip-counting has value on its own. I often use skip-counting when knitting and crafting. Instead of counting stitches by 1's, counting by 3's or 4's is much more efficient. Many people use skip-counting during their work day. A store owner uses skip-counting to take inventory of products. It comes in handy when playing games and in estimating. Since skip-counting is so valuable and can be fun to learn, it shouldn't be skipped.

#### Math Concepts Based on Skip-Counting

Multiplication
Division
Lowest Common Factor
Greatest Common Factor
Adding and Subtracting Fractions
Reducing Fractions
Factoring
Prime and Composite Numbers
Recognizing Number Patterns and Sequences

#### Multiplication and Division

Numerous math concepts are based on skip-counting. Multiplication, for example, is directly related to skip-counting. The numbers in the list above are the answers to the multiplication tables.

4: 4, 8, 12, 16, 20, 24, 28, 32, 36, 40

Skip-counting by 4's, referring to the above list, 4x1=4, 4x2=8, 4x3=12, 4x4=16 and so on. The answers are the same as the list of skip-counting numbers. Therefore, if kids learn to skip-count, they have already memorized the answers to the multiplication tables, before being asked to multiply. In other words, if children understand what skip-counting is and how to do it, multiplication becomes second nature.

The concept works equally well with division. Again, referring to 4's as an example: 4÷4=1, 8÷4=2, 12÷4=3, 16÷4=4. In this case, they have memorized the problems, but can count up to the correct answer.

#### Greatest Common Factor and Lowest Common Multiple

Greatest common factor (GCF), Lowest common multiple (LCM) and factoring are concepts taught in conjunction with fractions. Likewise with multiplication and division, having a good handle on skip-counting eases understanding of these concepts.

For example, the greatest common factor of the numbers 12 and 16 is 4. Why? Because both 12 and 16 are part of skip-counting by 4's. They are also both part of skip-counting by 2's, but the "greatest" word in the question requires the greater of the possible numbers. This answer of 4 can be visually seen by scanning the above list of skip-counting numbers and finding the biggest number that contains both 12 and 16 in its list.

Lowest common multiple is related to the greatest common factor in a similar way that division is related to multiplication. For example, 21 is the lowest common multiple of 3 and 7 because when referring to the list of numbers above, 21 is the lowest number in both the list for 3's and 7's.

#### When to Begin Skip-Counting?

If a math curriculum does cover skip-counting, the lessons usually begin around 2nd or 3rd grade. In general, this makes sense because kids should have a good handle on counting the numbers up to 100, counting backwards, and have a basic understanding of addition and subtraction. Although counting to 100 should really be second nature before beginning skip-counting, the other concepts could be mastered in conjunction with skip-counting. So for many kids, 2nd or 3rd grade works just fine, but kids as young as 4 or 5 years old can begin to master skip-counting.

Skip-counting by the numbers 2 and 5 usually comes first, because they are the easiest. Next it's best to work the way through the numbers concentrating on one until it is mastered as kids can become confused by advancing too quickly.

#### What's Next?

Once the child can skip-count well with all the numbers, or with any one number, the concepts of multiplication and division can be introduced. By placing effort on skip-counting, and making it fun, the pain parents often feel when teaching multiplication can be greatly reduced.

When my oldest daughter was about 4 years old a neighbor and friend of mine asked me, "Do you know how important skip-counting is in learning to multiply?" No was my answer that day, but I quickly learned how right she was. I followed her advice and used this method with all three of my own children who each learn very differently. Despite their differences, they all had fun learning to skip-count and rapidly learned follow-on math concepts. If you have a young child who has not begun learning math, are struggling to teach multiplication, factors, or fractions, or have an older child that could use some review, I highly advocate for a little skip-counting practice.