Comments

"On Friday and Saturday, there were a total of 200 cars in the parking lot of a movie theater. On Friday, 120 cars were in the parking lot."

Cars come an go in a movie theater parking lot. Is this at one point in time or was there someone there who tracked each car as it came in and left? What if some cars were in the parking lot at midnight? It would have been less confusing to talk about how many tickets were sold each day.

Of course, a major test taking skill is to be able to figure out really bad problems. I remember one vague test question in college where I did a brain dump and filled a blue book. The professor gave me a 'C' and called it "fair" (as in 'C'). No other comments. I never did find out what he wanted us to tell him.

-- SteveH - 09 Mar 2006

a major test taking skill is to be able to figure out really bad problems

Well that's the thing.

This is the Real World, and in the Real World test items are written in confusing prose.

Two weeks ago Christopher couldn't have solved this problem no matter how well it was written.

-- CatherineJohnson - 09 Mar 2006

I remember one vague test question in college where I did a brain dump and filled a blue book. The professor gave me a 'C' and called it "fair" (as in 'C'). No other comments. I never did find out what he wanted us to tell him.

jerk

-- CatherineJohnson - 09 Mar 2006

What was the procedure he used to solve it? I know Saxon spends some time reducing the fraction and then multiplying by 100%, which then becomes 100 over one. It's like an extra step if you don't immediately know how to get the denominator to 100 through equivalent fractions, but it's good for kids who still can't quickly solve it in their heads.

-- SusanS - 09 Mar 2006

I'm just now beginning to be able to persuade Christopher to reduce the fraction - Ed's been bugging him about that, too.

He used the ratio-proportion charts, and did it quite rapidly.

Then he could see that if Friday's 120 cars were 60% of the total, then Saturday's cars had to be 40%.

That's one of the reasons Saxon (& Dolciani & Brown) use the charts; they hammer home the idea that if you've been given one percent, you've been given two other percents as well:

If you know one of two things is 60%, you also have the figure 100% for the whole, and the figure 40% as the other part.

These charts are fantastic for teaching kids that ratios imply a third 'hidden' number, too.

If the ratio is 3 to 4, the whole is 7.

I never knew that!

-- CatherineJohnson - 09 Mar 2006

Those charts are worth their weight in gold.

I also LOVE the technique Dan posted, which I'll get pulled up front in a post and logged into the Index & the Math Lessons section...

-- CatherineJohnson - 09 Mar 2006

I'm doing them to death in Saxon 8/7, but they're not in 6/5 so far. Maybe later, I don't know. Right now percent is in the baby steps stage, I guess. I think he's starting to get overloaded on procedure and I'll need to slow it all down and keep it simple before moving to another way of arriving at it.

If the ratio is 3 to 4, the whole is 7.

I never knew that!

Lol! I had one of those "duh" moments, too. But only after I spent 15 minutes reducing some huge fraction before I figured out that I had done it the hard way. Sometimes it's just sitting right in front of you. I can't imagine how many problems I've solved over the years in the most round-a-bout difficult way while the math heads probably went for the easy, efficient way. That drives me crazy. Couldn't somebody have mentioned that to me when I was in school instead of assuming I had any common sense? Heck, they probably did several times and I wasn't paying any attention.

-- SusanS - 09 Mar 2006

I can't imagine how many problems I've solved over the years in the most round-a-bout difficult way while the math heads probably went for the easy, efficient way.

This is a CONSTANT in my life.

DUH

DUH, DUH, DUH, TRIPLE-H DUH

-- CatherineJohnson - 09 Mar 2006