## Friday, December 2, 2016

### Test #4 (Days 68-69)

Today I give the fourth 100-point test of the year -- the first such test of the trimester. For the eighth grade, this is on volumes of cylinders, cones, and spheres.

But I'm worried about this test. Going into it, some of the students feel that they aren't anywhere near ready for this test. Because of this, even though I haven't graded them yet, I fear the worst. This raises the question, am I teaching this lesson correctly? Of course, it doesn't help that I used a day they could have reviewed the material for science instead.

The problem is that I'm using the Student Journals from the Illinois State text -- meaning that I'm bound to teach it the way it's presented there. Sometimes, the text simply gives practice problems without explaining how to do the problems. In the case of these volumes, the text doesn't even bother to give the students the formulas!

Now let's compare this to the way volumes are presented in the U of Chicago text that we used on the blog last year. That text doesn't even distinguish between prisms and cylinders (as both of them are essentially V = Bh), nor between pyramids and cones (as both are essentially V = 1/3 Bh). But Illinois State doesn't even mention prisms or pyramids, because it's sticking to the actual standard:

CCSS.MATH.CONTENT.8.G.C.9
Know the formulas for the volumes of cones, cylinders, and spheres and use them to solve real-world and mathematical problems.

This could be a good time to take advantage of the packets that I'm now handing out. One of the pages could have given many, many more examples -- and I could have come up with my own rather than depend on the Saxon Algebra 1/2 text (which confused students because it gave formulas for surface area as well as volume).

I sing the "Measures of Center" song again in class today. I consider switching out to the Square One TV song "Draw a Map," but I don't -- and besides, the seventh graders seem to enjoy "Measures of Center" even though it's a sixth grade song.

Still, I'll post "Draw a Map" right here on the blog:

# Draw A Map

Oh, whoa-oo-oh
I’m coming back to town; I’d like to see you
I know it’s been a long, long time
I don’t know how to get there, since you moved
But I have directions from a friend of mine:
It’s five miles right, then five miles left
Then a mile down the road
I come past a tree, and wait for a light
How I’ll remember this, I don’t know!
He said, I’ll draw a map so you’ll find me
I’ll put it in scale and you’ll find me
I’ll just make an inch stand for a mile
I can make an inch stand for a mile
So he drew a map, a small but good one
Marking in an inch for every mile
He put in all the trees, and lights and landmarks
And I knew it would lead me to him after a while
So a mile down the road was an inch on my map
He brought it down to scale
The map is the same as the route to his house
Just smaller … in every detail
He said, I’ll draw a map so you’ll find me
I’ll put in a scale and you’ll find me
I’ll just make an inch stand for a mile
I can make an inch stand for a mile
He said, I’ll draw a map so you’ll find me
I’ll put it in scale and you’ll find me
I’ll just make an inch stand for a mile
I can make an inch stand for a mile

This is a two-day post. Coding will be on Monday, and my next post will be Tuesday.