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The only information about this concept provided in the textbook. The experiment design is shown here as well. [click on image to enlarge

At our last science subject meeting, the 6th grade science teacher called out for help on a lesson that she felt was a disaster and needed to reteach. We decided to plan the lesson as a group. All of the science teachers looked at the chapter in the textbook, which was about bridges. We were confused. It took about 15 minutes of intense thought, guessing and discussion to decide on a realistic objective that students could meet by doing the suggested experiments and reading the text: students will learn how to make arch bridges and suspension bridges stronger by adjusting the distance between the top of the arch or pillar and the road. None of us knew much about bridges, the textbook didn’t make these concepts clear to us, and there is no corresponding teachers’ guide.  We were at a loss about how to approach it. Thankfully, Steve and his scientific mind came to our rescue.  He explained the concepts to us and how the suggested experiments could illustrate it. We decided that we would have the students do the suspension bridge experiment. That would take up a whole period, so we revised our objectives to focus only on suspension bridges. It had taken the whole team of teachers (which included several teaching college graduates, one ex-doctor and one Harvard graduate student) most of the meeting time just to figure out what the heck this lesson was about.

The next day, Steve, two science teachers and I got together to try out the experiment and plan the lesson. This process took nearly two hours.

The research question is: Do taller pillars need to bear more or less pressure than shorter pillars on suspension bridges? Two chairs are used to represent the suspension pillars and an object is dangled from a string between the chairs to represent the weight of the road and cars (see diagram). We had to run through the experiment a few times. As we ran through the experiment, we found that some parts would obviously cause chaos or confusion when students ran it themselves. The textbook gave no detailed instructions, so we had to think of ways of setting up the experiment and giving instructions that would prevent this from happening. For example, the book doesn’t even remind students and teachers that all other variables (such as the distance of our hands from the chairs) need to remain constant.

Finally, we had to think of how to translate the experiment into more concrete terms so that it can apply to bridges in real life. This is more difficult than you would think. The purpose of the experiment is to figure out whether the pillars should be built taller or shorter, but instead of heightening and shortening the chairs which represent pillars, the experiment asks us to raise or lower the object representing the road. Students would naturally come to the conclusion that the road should be built lower, and not that the pillars need to be built higher. After several attempts, we finally came up with a process for enabling students to come to the correct conclusion.  We proceeded to work out the nitty gritty logistics of the lesson (how to group students, how to introduce the lesson, how to divide materials etc.)

This lesson was hard enough for us, and we had the advantage of  very collaborative colleagues, the support of a university math major and a firm belief in letting kids experiment. No wonder most teachers just give up and have the kids memorize the puny text boxes. This leaves their students worse off than before because the text boxes don’t even fully flesh out concepts like the old textbooks did. I’m delighted to see that the Ministry of Education wants to move away from memorizing and teaching from the textbook, word for word. But as they pull out long text that directly feeds knowledge to students, teachers need to be trained and given resources to understand what they are teaching and how to teach it.  This is a need that we are now working to fulfill. After working through how to teach this lesson, and many others like it, we will create detailed and practice-based resources for other rural teachers.