Multiplying and Dividing Positive and Negative Numbers

Continuing the Rules for Positive and Negative Numbers:

Multiplying and Dividing 

I wanted to continue with the rules for positive and negative numbers because the rules for adding and subtracting were tricky.   
Fortunately, the rules for multiplying and dividing are a little easier and after working with addition and subtraction hopefully students think so too.

Word Wall

In my research this week I can across the term fact family.  I liked what I learned about it because it reminded me of previous examples we've seen where the teacher selects specific numbers to teach a lesson.  Fact Family falls into this concept.  The fact family helps us understand the relationship between operations.  I'll delve deeper into this concept in my next blog.

Fact Family:  A group of math facts or equations using the same set of numbers.    

Multiplication Rules

1)  A positive times a positive equals a positive
                            5 x 5 = 25

2)  A negative times a negative equals a negative
                          -4 x -4 = 16

3)  A positive times a negative equals a negative
                          5 x -4 = -20

4)  A negative times a positive equals a negative
                          -5 x 4 = -20 

Division Rules

The rules for division are the same as the rules for multiplication.

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Flocabulary

Our social study teachers show the Flocabulary Week in Rap every Friday.  The students love it!  They use hip-hop rhythms and rap lyrics to get students excited about learning.  I had no idea they covered every subject and had lessons that aligned with state standards.  You have to pay for the service.  The attached video is 3:18 in length, but I don't have an account it only shows the first :40 seconds, you'll get a feel for what they do though.       

https://www.flocabulary.com/unit/multiplying-dividing-integers/  (3:18)

Poster

This poster demonstrates the rules for all of the operations.

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Conclusion

It is so important that students learn these rules.  Teachers need to demonstrate then in several ways to their students so they really grasp them.  They need to hear them, see them and use them in order to really understand them.  I'd recommend using manipulatives like chips or the - and + spacers we learned about in class.  Find interesting videos on the topic and allow students to work together to reason out why these rules work the way they do.  Also, have students apply them to real world problems to so they can connect meaning to them. 

Sources:

1 - https://www.youtube.com/watch?v=L1ZNw8Antv8

2 - http://www.loisterms.com/lois21.htm