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Questions about sound

April 30, 2013

Students asked some great questions today as we started our two-day long chapter on sound. I want to briefly jot down what we did with some quick thoughts about minor things that I think helped make the lesson successful.

I started by asking students to call out different ways of making sound, saying that I wanted to come up with list and then look for common themes. I wrote the list (talking, guitars, hitting objects together, etc.) on the overhead while students called out ideas and students quickly hit on the idea of vibration. Once students pointed out vibration in all of our examples I asked them if they had any examples where it wasn’t clear whether or not there was anything vibrating. One student came up with the sound of your stomach growling and I added a whistle to the list. At this point I asked students to discuss in their groups and try to come up with things they think they know about sound and questions they have about sound.

I’m glad I did the first part as a whole class. I had debated having students do the list of sounds and common themes in their groups. I think if I had gone that route students would have felt “done” and would have filled their whiteboard after listing some sounds and identifying vibration. Doing the first (easy) part as a class I think helped push groups to go further on their own.

After the group brainstorming I had students write ideas and questions on the board. The ideas mostly focused on vibrations, vibrations of some medium, faster vibrations mean higher pitch. Questions included ‘How does a seashell make sound?’, ‘How does thunder make sound?’, ‘What happens when you lose your voice, do your vocal cords just stop vibrating?’

Sometimes when I have groups whiteboard ideas/questions everyone comes up with the same things. This time there was a lot of variation in whiteboards which is why I asked students to share their ideas on the big boards. This variation could be due to some combination of:

  1. Doing this activity at the start of the chapter before students have a common framework for thinking about questions/explanations.
  2. Sound seems like an approachable topic with which students have varied experiences.
  3. Sound often receives less coverage in science classes compared to forces and circuits. This may free students from feeling like they are supposed to know the answers already.

 

We went through the ideas one by one sometimes doing a demo to verify the idea and sometimes asking for everyday experience to support the idea. When asking what evidence we have that sound can travel through water one student brought up sonar. I asked the student to explain a little further and after he finished I noted that it sounded like he was saying that another idea we have about sound is that it can bounce off things. I added this to our list of ideas on the board.

Later in class a student asked about whispering spots in buildings. I opened the question up to the class and another student explained that it had to do with acoustics and talked about the room reflecting and channeling the sound from one location to another. I was pleased the student voluntarily went past “acoustics” to describe a mechanism in terms of reflections. I don’t know if the student’s explanation was aided by the earlier discussion of sonar but I’m glad I didn’t miss that opportunity to add reflections to our class “framework” for thinking about sound.

I’m also getting better at assuring students that their questions will be answered but maybe not today and letting them know why. I sometimes have the habit of saying ‘Good question. That’s something we should think about.’ or ‘Good question but we aren’t ready to answer it yet.’ This can sometimes feel like a brush off to a student or like I am wedded to my lesson plan (neither of which are usually the case). When the student asked about seashells I told her that there was a demo I would bring in Thursday to help us answer her question (rather than just saying ‘Good question’ or ‘We’ll get to that on Thursday’). When a student asked about losing her voice I said that there are some other ideas we will want to help us answer her question and that we’ll be better prepared to answer her question on Thursday.

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