Even after almost convincing my 8th graders that air had no mass I still moved them forward and hope that they remember all the different gasses that make up our air and how each gas has an atomic weight, which would lead to the reasonable connection that air does have mass. It is, after all, made of something.
As part of my Science PLC work our high school biology teacher and I were going to see what our students understood with regards to trees and from where they get most of their mass. From Page Keeley’s book Uncovering Student Ideas in Science, Volume 2: 25 More Formative Assessment Probes we used the Giant Sequoia Tree probe. Basically the probe asks students to think about where a giant sequoia tree gets most of its mass from and provides a list of items such as sunlight, water, CO2, O2, chlorophyll and other things. Students worked individually to think about it, choose one and write about why they think that was the correct substance. Then I had students share with their small teams. On their papers they drew a line of learning. Under the line of learning they recorded any new information they got from their partners.
After they had time to share I gave each team a whiteboard, a board marker and they shared erasers to draw and write their best ideas. Each team got up and shared their whiteboard response with the class. Students were then able to ask each other questions. Here is some video of student teams sharing and discussing:
This was just the beginning as students raised more questions than answers. We’ve spent the time since then looking up what trees are made of and where they get their matter from to see who got it right. You can find their answers and links to websites they found (they were supposed to provide evidence from multiple sites because there are quite a few sites out there with misinformation! No duh, huh? Cha cha seemed to be a favorite search site for students even though it was hit and miss) on our Class Blog – scroll and on the right choose 8th graders or look for blog titles on the left hand side under student entries.
We are getting ready to start investigating and studying plants so hopefully this little excursion will be helpful.