To show how an area is made be sure to trace your block exactly, then label the dimensions

4 . 5

X

4.5

Then count the squares to see if your mathematics matches the image. Rember when we multiply decimals if we say what it is orally, then the answer makes more sense. In this case, tenths x tenths = hundredths.

1 2 3 4 .5

5 6 7 8 .5

9 10 11 12 .5

13 14 15 16 .5

.5 .5 .5 .5 .25

..

Use expanded form for easy multiplication.

4 + .5

x 4 + .5

16 + 2 because 4 x 4 = 16 and 4 x .5 =2

2 + .25 because .5 x 4=2 and .5x.5=.25

Total all for 20.25 Does that match the grid?

To find the surface area of a block you have to think about how many rectangles are there in a block. Are all faces congruent?Do some have different dimensions than the other ones? It might help to remember that tops and bottoms match (2x) and sides also match up (4) in rectangular prisms

Top is opposite

its base.

Can you think of when it might be handy to know surface area of a rectangular shaped prism....

Students will then be given several rectangular prisms to find the surface area of by tracing on cm graph paper.

Students should do a minimum of four examples in the class, and one more at home for homework.

The redpaint problem will follow for the POW.