John's Scribepost for December 5th,2010

Sup guys today in class we talked about scale and scale factors.
The first thing we did was this:

Scale : Proportional Reasoning

Image : Actual

Then we did a problem is was:

A B Aprime Bprime
1 : 7 X : 23.5

But before starting with the question Mr.Backe
explained something about where the primes should go and where they shouldn't go.

Works: A/Aprime = B/Bprime

Doesn't Work: A/Aprime = Bprime/A

Then we started on the question

1 : 7 x : 23.5

1/x = 7/23.5 so you would cross multiply the numbers so 7 multiply x equals 7x
so you would put it like this.

7x/7 = 23.5/7 then 7x/7 would cancel each other out so you would divide 23.5 by 7 and your answer will be 3.36
X=3.36

After we were done talking about that question we did another

2 : 3 11 : x

2/3 = 11/x so as the last question went you would multiply 2 by x which would equal 2x and 3 by 11 which would equal 33. So the format would be like this

2x/2 = 33/2

2x/2 would cancel each other out and you have to divide 33 by 2 to get your answer of 16.5.
X=16.5 Mr.Backe said it was called By Inspection.

After finishing more questions we reviewed the

mm cm dm dam hm km
mi ci di 1000 deca heca kilo
1000000 10000 m 100 10 1
100000 l
g

Then Mr.Backe asked how many 1cm would you need to reach 10km and the answer was you would need 100000 1cm to get the 10km.

Then Class Ended.

Homework:
Read 4.2 139-142
do SYK
CYU 1-3
Practise: odd or even
Apply: 13-16 or 15-19
Extend: 20 and 21 or 21 and 22 (you have to do 21 for sure)

TEST ON WENSDAY ON SCALE AND SCALE FACTOR

If I got anything wrong tell me so I can fix it!!!

JOHN!