We will be learning how to find the surface area of some solid figures.
The solid figures we will be focusing on are rectangular prisms and cubes.
The formula for both:
SA= 2(LxW) +2(LxH) +2(WxH)
OR
SA= 2x(Lxw)+(LxH)+(WxH)
However, we will be using the "Y" method to figure out the surface area.
See images below for quick tutorial. (These are from our flipchart so students should be familiar with, and it will hopefully trigger memories from class.)
- Draw a Y
- Take the three numbers (the length, width, and height) and put them on the corner of a Y.
- Then multiply the two corners putting the answer in between each spot (notice the 30, 20, 24.)
- Take these three numbers and find the sum by adding them together.
- Double that sum by multiplying it by two.
The reason you must double is because that is only one half of the rectangular prism. You have to double it to take care of the remaining half to find the complete surface area.
VOLUME
We call this the "easy" method because it is one of the easiest formulas to memorize.
Volume=Length x Width x Height
Basically, you take the three numbers available and multiply them all together.
Watch out for kids getting confused between Volume & Surface Area. This is normal, but try to avoid the confusion by asking them to explain what they are doing when they do their sample problems and why. You can even create your own by making a mixture of any three numbers.
Signing off, Mrs. Burger :-)
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