Catching the Wave!
Lesson 2 of 8
Objective: Students learn the meaning of amplitude, crests and troughs.
I opened up the lesson today by telling my students that yesterday's lesson was a great way to understand more about water waves and also develop some more questions. I asked them to repeat what we decided was true about waves that we saw. One student raised his hand and said, "We know that the faster the bottle rocked, the bigger the waves got."
"Yup. That's true! But, what if, " I asked, " there is a shape to waves that forms a pattern ? If there is a pattern, can we measure it or make sense of it? Does the shape have any meaning?"
These questions were essential in getting them to think more deeply about the next part of their investigation. I wrote the word "Amplitude" on the white board and pronounced it, telling them that they would work deciding what this word means through looking at the videos of their waves. We would be looking at the wave without the cork videos at 52 beats, 88 and 144. They needed to carefully freeze a good shot of a clear picture of a wave.
I turned on our Smart Board and brought up Using What We Have Learned and Observed to Move On! SB file to help guide our lesson along. I also passed out the Wave Vocabulary worksheet. Students used their science notebooks to take notes and keep record of any observations. They were encouraged to write down questions as they thought of them during the investigation.
The first page of the notebook file was the guide post to my instruction as they began finding the movies of their waves and then screen shot them. When they had found all of them, I asked them to really look at each photo and notice the differences, using the questions on the first page of the SB file to direct their discussion. When all were caught up, I moved to the next part of the investigation.
Sketching and Defining
I settled students down by giving the hand signal that means to listen. I had heard some interesting dialogue, so I opened up the floor for comments and questions. I asked if they wanted to share observations or questions. One student raised his hand and made the comment that there weren't reallly any waves at 52 beats. Others agreed to say they were very small. I reminded them that we had established that the day before, but that I wanted them to now sketch their screen shot wave photos to learn more about patterns within waves. Then, I wanted them to outline the wave in another color.
I gave them each a white piece of copy paper and showed them how to fold it in thirds. I explained that I wanted them to sketch each sample from slowest to fastest waves in each section we have created. They got busy drawing their photos they had chosen. The dialogue was interesting to listen to as they sketched. Some wanted to be very detailed using color and shading Others chose to just simply sketch an outline. I didn't place any demands on them as long as it represented what was on their iPad photo screen. At one point, I had to clear up some confusion with one group who misunderstood, thinking they had to sketch from each video. I roved the classroom and visited students, asking them to explain and share with me what their thoughts were about their drawings and what they noticed about the differences in the waves at different speeds. When we were finished, I told them that I wanted them to share their observations as well as decide what the word "amplitude" might mean. The next steps would be leading them into applying the vocabulary through their experience.
I asked my students to share their thinking about their waves. I asked them if they could draw some conclusions about what they noticed and if their conclusions were any different from the day before. They still all agreed that the more force, the greater the wave. I explained that our goal was to decide where the amplitude is of the wave. I sketched a drawing of a wave, similar to what I was seeing them sketch. I drew a line in another color to represent where the altitude could be measured from. Since these wave did not have full cycle, I drew the line where the wave became flat, horizontally across. Where I wrote the word amplitude, we started to discuss what the word amplitude sounded like and I wrote that down. I asked them what they thought it might be telling them that it occurs in the wave. Several students guessed that it was at the top ( crest). I labeled the top "crest" explaining what a crest of a wave was.
I asked another student to come and point to another spot where it might be on the drawing. He came up and pointed to the trough. I labeled it trough and asked them where another place could be? No one could connect the line to the top of the wave and so I finally labeled the amplitude, explaining that it was the highest point in the wave cycle. I asked them to draw it and label it in their drawings so they could remember. Then, I revealed the second page of the SB file. I asked them to check their drawings to make sure the labels matched the picture. Then, we discussed the patterns that they saw. One student explained what she noticed from her drawing and could draw conclusions about the increase in force and the result. I explained that these waves are shallow waves and that the motion is contained in the bottle, but still gives us a good scientific model to understand.
When we were done sharing, I asked them to cut out and glue the word "amplitude" into their notebook and sketch the picture they saw on the SB with and short sentence about what amplitude is. I also continued onto page 4 to explain wavelength. I asked them to glue the word "wavelength" in their notebook near the bottom of the drawing in their notebook. We defined each word using what we have observed.
I stopped the SB file at page 4 and saved the rest for our next investigation where we will discover what the transfer of energy looks like. As I stopped the students, I asked them to share some questions from their notebooks. Students asked questions like, how do waves wind up being flat? and how many sizes are there? These are questions I never would have thought of! We discussed the reasoning and observations from the real world to answer them one by one.
I closed by telling them that tomorrow we would understand how waves transfer energy.