Math 7 ( Period 4)

Justifying the properties

What are properties- They are characteristics of math operations that can be identified

Why are they your friends... your BFF  you can count on properties. They  always  work. there are no (0) COUNTEREXMPLES

COUNTEREXAMPLE- an example that shows that something does NOT work.

It counters what you said!

Because you can ALWAYS count on properties, you can use the to JUSTIFY what you do mathematically.

JUSTIFY = giving a reason for doing what you did and you’re reasons are your BFF’s the properties

There are 2 parts of justifying

1) First of all what did you change  or if you’re looking at what someone else did, what changed? (did the order change? did the (  ) change? Has anything been simplified?)

2) What allowed you (or them) to make the change?

(Commutative ?  Associative ? Distributive?)

Example  you’re given (5)(565)(2) but you change it to:

(5)(2)(565)

(10)(565)

5650

JUSTIFY what you did... What did you do to get the solution?

1) You changed the order

2) Commutative Property of Multiplication allows you to change the order

This time you are given

(565)(5)(2) but you change it to  (565)[(5)(2)] and quickly get 565(10) = 5650

Justify... ( What did you do to get your answer?)

1) you put in a set of [  ]

2) Associative Property of Multiplication allows you to either add or take away a set of ( ) and [  ] are part of the group in ( )  

Why do you think Aunt Sally would dislike these properties intensely?

Because properties are the EXCEPTIONS to her RULES (Order of Operations or PEMDAS)

She’s happy though that sometimes your justification can be ORDER OF OPERATIONS ( in other words you just simplified or did the math in the proper order of PEMDAS)

Again why do we love properties?? Why should you care?

Because they make the math easier—sometimes!

Aunt Sally hates them because they allow us to break her rules!