CER – Developing Structures

Evidence. It’s challenging for my 7th graders to keep coming back to evidence. Personally, I’ve struggled finding the right scaffolds for students to have them put together investigations and share their thinking. The following is my latest installment based upon some past work with Paul Andersen (@paulandersen) and continual shifts in thinking towards NGSS practices. In the end, student goals are to have strong conversations about their investigations, clearly model design, display key evidence and conceptually model their ideas.

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(Link to above document)

The structure above is used at the end of an investigation though students need to show their experimental design. (A topic for a different time – how much emphasis are people putting on the physical writing of a procedure versus setting up the experimental design and then moving forward?)

Experimental Design: In the experimental design, students create a model that shows their set-up with the independent, dependent and controlled variables clearly indicated. Below are a couple of student examples for an investigation where the mass of a dynamic cart was varied as students examined change in velocity with constant force or an applied force was varied.

What I like:

  • The visual nature of setting up an investigation through a model.
  • Highlighting the variables. My students are not always 100% confident on independent, dependent and controlled variables. This color connection makes them again talk about the variables. They also quickly realize if parts are missing from their model.
  • There is a focus on the experimental set-up. Students are talking about the parts of the investigation they are working with.

What I wonder:

  • For seventh graders, is this good enough? In the past, I’ve spent a lot of time word smithing on procedures and I’m not sure that that is necessarily time well spent. What do I really want? I would like students to have a strong foundation in designing investigations that focus on a relationship between an independent and dependent variable. I would like students to truly grasp the need to keep all other items controlled.
  • How can I mix in a strong foundation of procedure-type vocabulary that students then show on the model?
  • What can be done to improve on the current model? Does more need to be done regarding the independent / dependent variable relationship? What about the controlled variables – how do the key ones really stand out?
  • Multiple Trials – One group wrote to repeat for every trial though they did not indicate how many trials would be necessary. Maybe I should make this more specific.

Data: Once the set-up is ironed out, students move to collecting data. Organized data tables are challenging to set-up! We eventually get data tables constructed in a spreadsheet and students begin collecting. This post is more related to the workup of ideas so let’s move to the display of evidence.

What I like:

  • Paul Andersen was the one that led me to showing all of the data collected in trials on a graph. In the past, students showed the average only but a lot of information was lost. We now have conversations about the range of data and the confidence level of groups in whether or not they have a strong data set.
  • The graph is another place where we check in on independent and dependent variables.
  • Physics! We got reproducible data almost across the board and it really does make a difference.
  • Working up the data into a graphical display and then having students write a claim.

What I wonder:

  • Students are doing more with data in spreadsheets though get really turned around when it gets to graphing with the software. I like the investment of time to go into discussing the data instead of physically graphing but I don’t have a good solution yet for graphical displays. (I’m toying with Excel/gSheets, Desmos and CODAPany others?)

Conceptual Model of Claim: In support of the claim that student groups generate based upon their data, I’m working with the idea of a model to explain ideas. Evidence is shown on the graph, so the focus here is more in showing the big idea of the claim. This is definitely a work in progress and in need of refinement.

What I like:

  • Students are returning to the relationship of the independent and dependent variables.
  • By having this piece not focus on numbers, students talk more about representing their ideas.
  • A focus is placed upon the claim being a representation of the data. Our conversations were around what patterns are in the data and how can this be shown.

What I wonder:

  • Dot diagrams were provided as a way for students to model their thoughts. In other areas, is it good for groups to have similar models for better comparison or better to have groups represent in any way they like?
  • What additional description should accompany the conceptual model. Is the claim and the model enough?
  • Many more thoughts running around…

Reasoning – With my 7th graders, I’m finding that more structure is still a good idea when writing a claim. We return to the relationship of the independent to dependent variable and I want to see students including specific information from their trials of what was changed and what was measured. My focus has been on developing a solid reliance on evidence that I hope can then be used to eventually link to strong reasoning.

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