June 7 Journal Q about variables

Guest

Hello Ms. Cie,
we had a really fun time drawing pictures of Rachael's experiment to understand how she was setting up her trials. I cut and pasted her experiment description along with your question onto a piece of paper. Then we read the journal entry and tried to answer your question first without pictures. the whole time we had the picture of Rachael that you sent because it made it seem like she was actually doing the experiment in front of us, and we could see the container where she was doing the experiment and it helped us visualize it. Some of us could figure out at least two of the variables ( controlled and responding just from the text) then, we drew pictures of the four containers and labeled them with the labels ( control, Treatment 1, 2 and 3), then we labeled each with what Rachael was putting into each container ( as Rachael watched us).

As we drew the pictures ( 1 big picture with different students drawing and others reading and telling them what to draw) and all of us drawing on our own piece of paper) the experiment became clearer and clearer to most of us so we came to the consensus that Rachael's controlled variable was the container with 18 Liters of the .2 micron filtered water.
The manipulated variable was the stuff she added to each container that was different: control: .1 micron filtered water, tx 1: 3g of peat ( not Pete *8smile**), tx 2: .8 g of wet ice algae, tx 3:18 g of wet ice debris ('crud' in 8th grade terms). The responding variable was the bacteria (numbers and types). The "type" question was what prompted me to ask for a picture of the stained bacteria to see if they were rods, or balls, or? and what color they stain. Rachael watched us do all this from the screen.

We did not tackle the analysis of the lipid membranes, maybe next year?

I have the papers we did this lesson on so you can see what your students did. You would have been very gratified and proud at their understanding of the three types of variables, and how many got it just from the text, then how many got more of it as we explored how to draw pictures to make text more understandable. They seemed to enjoy that part, it became very clear very fast which variable was the controlled variable as we write "18L of water" in each container. Ah ha's happened...lights went on over 8th grade science students heads...it was cool.

keep havin' fun Ms. Cie,
Core 1, 2 &3 and Dr. R