kitchen table math, the sequel: 8/17/08 - 8/24/08

Friday, August 22, 2008

Math Facts [UPDATED]

I have been using this website to quiz my kids. It does multiplication, addition, subtraction, and division. It allows you to review missed questions, set time limits, etc, etc...

My kids love it. I have my 3rd grader reviewing her addition facts, and my fifth graders doing multiplication tables to review (get them in the groove after the summer). After they get through the sequence, I will start them on subtraction and division.

They normally run 3 minutes tests and see how many they can answer correctly. They love it. I normally have to kick them off to let another kid have a go.

Thursday, August 21, 2008

Here’s a clue about why our schools are in trouble

If I didn't know anything else about our nation’s public schools, this one sentence from the WSJ article about merit pay in Denver would go a long way in explaining the trouble with our education system.
Nationwide, most teachers are paid based on two factors: education and experience.

Teachers take risks when they decide to teach middle-school math

The headline in the WSJ article says “Denver Teachers Object to Changes In Pay-for-Performance Plan”

Yawn

But the biggest rewards will go to early- and midcareer teachers -- and to those
willing to take risks by working in impoverished schools or taking jobs few
others want, such as teaching middle-school math.

No one who reads KTM regularly is surprised to find that teaching middle-school math is considered a job desired by few teachers. It must be darn hard to teach students who’ve emerged from elementary school not having mastered such things as fluency with multiplication tables, long division or fractions. These are considered by many mathematicians to be critical stepping stones on the way to higher-level mathematics. Instead, middle school math teachers might typically find students who have mastered things like math journaling, sorting colored manipulatives as a way to demonstrate they understand the “concept” of multiplication and pizza-slice fraction analysis.

Middle school math – where the math sh*t hits the fan.

PS – Actually, the entire article is worth reading.

The Denver teachers may decide to strike while the Democratic Convention is in town.

That could create some awkward moments. The Democrats don't want to anger
teachers unions, which are key allies. Nor do they want Denver's plan to fall
apart.
Merit pay did make a difference.

Before the plan took effect, she said, "we almost never sat down with our
principals to say, 'Where are our students now, where do they need to be and how
do we get them there?
' This really has changed the culture in our schools."

Tuesday, August 19, 2008

School starts, always a surprise

Of course, it's not a pleasant one. My 7th graders Algebra I teacher doesn't assign homework. Scientific studies you know.

Can anyone steer me to the pro and con scientific studies? I suspect all I need to do is go through the "homework" label, but the post is "therapy" nonetheless!

Thanks!

Monday, August 18, 2008

Math fun!

Class today, so while I'm gone, here are some "test your knowledge" quiz questions I have given my students. Each is easily answered with no more than simple descriptive statistics, but tests the student's knowledge of the concepts (as opposed to whether the student can calculate an arithmetic mean or standard deviation). A student sitting in front of Excel, SPSS, or SAS should be able to answer these three questions in three minutes.

Answers when I get back this afternoon.

1. A tire manufacturer produces a particular model tire whose tread wear life is normally distributed with a mean of 39,000 miles and a standard deviation of 5,300 miles. The manufacturer wishes to provide a guaranteed tread life for this model which would be exceeded by 98% of all tires. What tread life would meet this requirement?

2. The mechanical process which fills 10-lb bags of dog food is subject to random fluctuations in the amount placed in each bag. The amount placed in each bag is approximately normally distributed with a mean of 170 ounces and a standard deviation of 4.3 ounces. Determine an interval centered on the mean such that the weight of the contents of 99% of the bags will fall within that interval.

3. The scores on an exam are approximately normally distributed with a mean of 75 and a standard deviation of 10. If the professor wants 10% of the class to receive As, then what is the minimum score a student can get and receive an A on the exam?