Crushing

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On August 31 we investigated what happens to materials when they are crushed.

Making Predictions

I asked students to think about a soda can that gets crushed and a piece of paper that gets torn into 100 pieces. I asked them to answer these questions in their notebooks.

When a material changes shape,

  • Is it still the same material?
  • Does the amount of the material remain the same?
  • Why do you think so?

Students compared their answers in groups. We found that we had different ideas about what happens to the amount of materials when it is crushed.

Carrying Out the Investigation

We had already decided the class before on things we would test in our crushing experiment. All groups tested an aluminum can, a piece of paper, and a cookie. Then they chose two items from other available materials, such as aluminum foil, wood sticks, and cardboard.

Crushing

Cookie before crushing
Cookie after crushing

Students observed the properties of materials before and after crushing and weighed the materials before and after crushing. They gathered their data.

Analyzing and Interpreting Data

On September 1 we began analyzing our data to make sense of what happened during crushing. Groups looked for patterns in the property and weight data and figured out what those patterns meant.

I introduced the concept of evidence. We talked about the difference between evidence and opinion. We discussed examples of evidence. Evidence is important because scientists use evidence to make claims. I told the students that, as scientists, they would be using evidence to make claims. Scientists decide which claims are best by arguing from evidence. We discussed how scientists support or refute claims.

Creating Claim, Evidence, and Reasoning Collaboratively

We practiced making a claim and supporting it with evidence and reasoning. We made a claim about what happened to the type of material before and after crushing. We decided that the type of material was the same before and after crushing. We identified evidence from our investigation that supported the claim. For example, the cookie was black, rough, and dull before and after crushing. The foil was silver and shiny before and after crushing. Our reasoning was that materials have certain patterns of properties. If the material is the same, the properties should be the same.

We did notice that some properties could be different before and after crushing. For example, texture can change. The aluminum can was very smooth before crushing. Some students crushed their cans by stepping on them on the sidewalk. The rough sidewalk imprint changed the texture of the can.

Next Steps

Our next step in this investigation will be to make an evidence-based claim about the weight of the material before and after crushing. I’ve noticed in my circulating the room that some students have data that will support that the weight is the same before and after crushing, while others have data that will refute that claim. When we continue this investigation, I plan to have groups assemble their own claims, evidence, and reasoning. Then they will compare their claims, evidence, and reasoning to other groups, decide if they support or refute the claim and provide evidence and reasoning for that position. This will be our first scientific argument.

Before we have our scientific argument, I will show this video to review what a scientific argument is.

I will scaffold students’ scientific arguments with an organizer.

I added the level of certainty information to see how students respond to the discrepancies in their data and to connect to the video content. From my observations, I noticed there were issues with taring the scale that led to inaccurate measurements.

After each group fills out their organizers, they will compare their arguments with another group by trading papers. Then they will use sentence starters to give feedback about the argument.

Evaluating the Argument

First, they need to evaluate the argument.

  • Is the evidence relevant to the claim?
  • Do you trust the evidence?
  • Are there gaps in the cause and effect reasoning?
  • Is there another possible explanation?

Responding to the Argument

If they disagree with the argument they can:

  • Ask a question about the reasoning
  • Offer different reasoning
  • Offer a different claim. 
  • Look for other reasons for the evidence. 
  • Compare claims with known scientific facts. 
  • Make sure that all data is included.

If they agree they can:

  • Give additional evidence or reasoning

Supporting Student Responses

To support their responses, I offer some sentence starters.

To refute a group’s claim, evidence or reasoning they can:

  • (ask a question) Why did you think that?
  • (offer another reason or claim) I think that.. 
  • (look for other reasons) I think that happened because…
  • (compare to facts) I read (or was told)… 
  • (include more data) This data (share the data) refutes your claim.

To support a group’s claim, evidence, or reasoning they will

  • (Add more evidence or reasoning) My data showed that…

I am looking forward to my students’ first scientific argument. Stay tuned…

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