Rates of Weathering Lab

Don’t you just love it when your lesson goes well!  Whenever I do a lab with my sixth graders, I set is up as best I can – plan everything down to the smallest detail, but there is an element of randomness that cannot be controlled.  So once I get them started,  I always cross my fingers and hope for the best.  Many times I am scribbling down notes for small tweaks to improve it for the next time, but not today!!  Today went off without a hitch.  My students were motivated, they were focused, they got their experimenting done in a timely manner, and they drew accurate conclusions.  (Just a sidenote  – I remember early on in my teaching I asked my students to “draw conclusions” and the look of confusion on their faces – one brave child asked me, “How are we supposed to draw that?!?”)

Today’s lab modeled chemical weathering in the classroom – find it here!  We looked at how climate affects the rate of weathering.  We used alka-seltzer tablets to represent rock and the students worked in lab groups to create their own procedure to test our testable question:

“How does the temperature of water affect how fast an alka-seltzer tablet dissolves?”

The students had to create a procedure that included 4 different tests to test a different temperature.  They were given the following materials:  Hot water, room temperature water, and ice)  Here is one group’s procedure:


Some groups needed a little guidance creating a 4th test.  They all could figure out testing in hot water, room temperature water, and ice water, but then some got stuck.  I reminded them that temperature is like a number line so they could mix different amounts of the supplies to get different temperatures.  This was enough to get most groups going.  A few groups needed an even stronger hint so I would ask them if they thought they could make warm water.  Once all groups had their procedures made they were all very self directed since they created their procedures they knew exactly what to do.  It was beautiful.  I gave them 20 minutes to test to keep them focused.


We had new digital thermometers that the kids loved.   They measure to the nearest 1/10th of a degree and you can choose Celsius or Fahrenheit.  We got them for a future lab where we need precise measurement but since they came early we got to try them out.

After testing, the students worked on their conclusions.  The conclusion related our lab results to the effect of climate on the rate of weathering.  They read a short passage and then wrote a C-E-R conclusion.  Some students needed a little help getting started so I provided sentence starters on the ELMO.file3

It was a fun day of teaching.


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