Monday, May 25, 2009

Word Problem

I'm the mathematics coordinator of 3rd and 4th grades of my school in Chile. We are using the My Pals are Here Series. But I have a doubt, concerned to the fact that even though we are focused on solving word problems using the models methology and it makes sense to the girls when we are working together, they are still having problems when they are working alone, specially during tests. They start right away with operations but most of the time it is wrong, because they didn't visualize the entire problem. Do you have any suggestion? Should we continue with next chapter or work more on problem solving with additions and subtractions?

Question posted by Paula, a mathematics co-ordinator in Chile
As you have mentioned, when the students start straight away with the operations they are often wrong. They need to comprehend the problems well. Drawing a model will help them understand how the information are related. In simple one-step problem, it may not necessary to do so. But in a problem with a lot of information, this becomes essential for average students. Otherwise although they can read the word, they do not comprehend the information.

Also in multi-step problems, the students may not have the ability to monitor their thinking. This is metacognition. When we teach word problems, we should model and coach rather than explain. That way, we help them in developing the ability to think through the many steps in a problem.

Monday, May 11, 2009

Speed Problem...Again

A car needs 7 hours to travel from Town X to Town Y. A motorcycle needs 8 hours to travel from Town Y to Town X. The car leaves Town X for Town Y and the motorcycles leaves from Town Y to Town X at the same time. How long will it take for the car and the motorcycle to meet?
Speed Problems are frequently brought up. There are earlier entries discussing Speed Problems. See below.
So, how long will it take for the car and the motorcyle to meet. The standard joke is that we hope they don't!
That aside, we need to assume that the speed of the two vehicles are constant. If that is so then in an hour, the car travels 1/7 the distance in an hour and the motorcycle travels 1/8 the distance in an hour. The problem is solved when the distance travelled by the car and motorcyle add up to 1 whole. In an hour, total distance covered by both is (1/7 + 1/8) of XY. This works out to 15/56 of XY. In 2 hours, it is (2/7 + 2/8) of XY or 30/56 of XY. In 3 hours, 45/56. In 4 hours, 60/56. They would have passed each other in 4 hours. Can I leave it to you to complete the last step of the solution. It is by no means trivial but there are enough leads already.

Friday, May 8, 2009

Request for Presentation Slides

I am a 5th grade teacher in Fayetteville, NC. I had the amazing opportunity to attend your session at the NCTM Conference in Washington, DC a few weeks ago and was truly inspired! If possible, would you be able to email me a copy of your handouts and powerpoints used in your session? I would greatly appreciate it! Thank you for your time and amazing inspiration!
Laura, an American teacher
The presentation slides at the NCTM Annual Meeting & Exposition are available at Look for the conference that you are interested in and click on the pdf. The slides should download. The slides for my other presentations are also available here.