After reviewing the homework problems assigned for Lesson 7, students were reintroduced to the Copper Cycle. Because the Copper Cycle experiment involves steps that must be conducted in a fume hood, we opted to watch a video (below), with students taking observations on their Copper Cycle handout. For reference, students also received a copy of the Copper Cycle experimental procedure.
After the video, we discussed the concept of Conservation of Matter, transitioning to Lesson 8 in the textbook. Because Lesson 8 continues an investigation of the Copper Cycle, and we are unable to safely conduct that lab, we instead investigated the related concept of Conservation of Mass. Students participated in a classroom demonstration which involved combining baking soda and vinegar in a closed system and experimentally demonstrating that mass is conserved. We measured the starting and ending mass, noting the slight decrease in mass at the end due to experimental error (vinegar and carbon dioxide leaking slightly). At the end of the experiment, we removed the inflated balloon and noted a decrease in mass of 0.2-0.3 grams, indicating the carbon dioxide gas has a measurable mass. Students also noted the change in volume of the products as evidenced by the partially inflated balloon compared with the volume of the reactants.
For homework, students were provided with a copy of the Penny Lab to read over in advance of Wednesday’s class. Students were also reminded that a signed syllabus and safety contract must be turned in to enable participation in the lab.
After reviewing student work, one area that we clearly needed to spend some time revisiting was the concept of matter. In a system, the amount of matter does not change. Atoms are the fundamental unit of matter. When collections of atoms bond together they create molecules. The key point is that the number of atoms in a system will stay constant, while the bonds between those atoms (the molecules) can change. Stated another way, the amount of matter stays constant but changes form. This conservation of matter concept was introduced to students in 9th grade Integrated Science, and it is important that students understand the concept as they continue in their study of biology. To help visualize the conservation of matter principle, on Friday we watched a segment of the NOVA special “Hunting the Elements” beginning at 47:47 and continuing through the end of class. The explosions during the first segment of the video were accompanied by explanations of the rearrangement of atoms and release of energy, and students took notes to ensure understanding of the conservation of matter. Next, students learned about CHNOPS, the 6 main elements found within the human body (Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, and Sulfur). Students recorded the percentage of each element and learned to calculate the percentage of elements reported an pounds. Depending on time, some classes were able to watch the next segment on trace elements, while others finished with the segment on bacteria living in Yellowstone National Park. The complete video can we seen below or on Netflix.