Students took notes from the Lesson 9 PowerPoint, learning about the concepts of atomic mass, protons, and neutrons, and isotopes. Students also learned about electrons and the concept of electronegativity. They then worked together in groups of four to complete the Lesson 9 Worksheet. For homework, students were instructed to complete the worksheet, answer questions 1 and 2 from the end of Lesson 9 in the textbook, and then to read Chapter 10 in the textbook. Notes from the whiteboard are pictured below.
Students continued the process of writing up their egg lab reports using the school Chromebooks. Notes from the white board are pictured below. Students will have one last day to use the Chromebooks tomorrow. Students who finish early should “share” their report, written in Google Docs, with me. In return, I will share access to the student egg lab data from all four of my biology classes (open in Google Sheets). Students should analyze the data for trends, patterns, and consistency, using the spreadsheet to organize the data and calculate average mass from similar experimental conditions. Want to see our class results? An Excel spreadsheet containing annonymized student data can be downloaded here.
Students used the school Chromebooks to begin typing up their Egg Lab lab reports. Special thanks to our substitute, Mr. Burke, and I look forward to seeing the work students accomplished when I return to class tomorrow.
Every now and then we have to take a day of class to “sit and get” – a day of class where students learn and review important science concepts designed to help them make sense of their lab observations and use science to explain what they saw. Today was one of those days. Students learned about how the cell membrane works, focusing on the concepts of osmosis and transport. Students should review the Membrane Functions PowerPoint slide deck and commit the vocabulary terms to memory. The aquaporin claymation video included in the slide deck is also provided below for easy access:
In preparation for Lessons 9 and 10 in which the Periodic Table is introduced, students watched the first half of the PBS Nova video, “Hunting the Elements” – we finished at the 48 minute mark today. Students will have a substitute teacher tomorrow and will finish the video in class.
Updated 9/29: Special thanks to our substitute, Mr. Burke. He informed me students were able to watch through the 1:29:00 mark of the video. Students are encouraged to finish the video outside of class. Students should read Lesson 9 before class tomorrow and come prepared to extend their learning of the Periodic Table.
We concluded the Egg Lab with one final day of data collection. After students turned in the quiz they received yesterday, they had the opportunity to measure the mass of their egg one last time before making final observations. Some students elected to boil their egg, others dissected their egg, and some did both. Students noticed how some of the liquids turned the egg membrane a certain color, taking on the color of the liquid the egg had been in. Others noticed the cytoplasm also turned the same color as the membrane. Some students found the consistency of the egg cytoplasm to be very watery, while others had a more viscous consistency. Brave students also smelled the inside of their dissected eggs, finding them to smell like vinegar and perhaps also like the liquid they tested their egg in (chocolate milk and vinegar had a particularly memorable smell). These observations will enable students to update their models of membrane activity as we continue through the unit. Students were reminded to read pages 76-80 of the reading packet from Wednesday so that they are prepared to learn about the scientific concepts behind cell membrane activity on Monday. Students will also share out their final egg mass on Monday, and the class data will be posted then for analysis. Students will apply their learning from the lab, the reading, and our classroom discussions, as well as their analysis of the lab data to a lab report they will write next week.
Following up on the conservation of matter lesson from yesterday, students worked in groups to conduct a similar experiment to the baking soda and vinegar demonstration. Today, students were tasked with experimentally testing the law of conservation of mass by mixing known masses of vinegar and Tums (calcium carbonate), then capturing the carbon dioxide released in the experiment in a balloon placed over the flask. They were tasked with determining how much carbon dioxide is produced but the challenge was that, unlike the demonstration yesterday, they could not simply allow the carbon dioxide to escape into the atmosphere. After much trial and error, students gained practical experience working with various pieces of glassware, reagents, the digital balance, thinking through order of experimental operations, recording observations, and sharing their understanding of what was happening during the chemical reaction. We concluded with a discussion of the chemical reaction (pictured below). Students will meet tomorrow in the library computer lab to compile their findings into a lab report. Students were encouraged to take pictures or video into their investigation today and those can be incorporated into the lab report.
On this third day of data collection for the egg lab, students observed their eggs after 24 hours in the liquid they chose yesterday. Students once again gently rinsed their eggs and cups, then measured and recorded the mass. The eggs were placed back in the cups and then filled with tap water for one final day. Students shared out their egg mass data and we began crafting a model to help fit their observations. We focused on the eggs in corn syrup (they shriveled) and in distilled water (several popped), with students beginning to reason through what may have entered and left the egg across the cell membrane. We concluded with students receiving the Friday quiz to work on as homework and to help them focus their reading from the packet that went home yesterday. Students who complete the quiz as homework will have the opportunity to boil their egg in class tomorrow and observe the process of an egg boiling without a shell.
Class began with a brief review of where we left off yesterday with the Egg Lab, followed by students writing today’s steps of the experimental procedure. After being checked off for having written out the steps, students put on gloves and carefully rinsed their eggs and cups. They took the mass of their eggs (the “after water – 9/23” mass) and recorded it in their lab notebooks. Finally, they chose one of the offered liquids (distilled water, 30% salt water, 50% corn syrup, 10% dish soap, or canola oil) or used a student-supplied school-appropriate liquid. Liquid was added to the cup (enough to cover the egg) and the cups were scattered around the room for observation.
After adding the liquid, students shared out their egg mass data along with their selected liquid. The data were collated and will be available as an Excel file for analysis on Friday. The students then toured the room, making observations about the eggs after they had been in liquid for 15-20 minutes. During the last few minutes of class, students began thinking about how they would draw a model to represent the movement of matter across the cell membrane. Students also received a reading packet and are responsible for reading pages 76-80 before the quiz on Friday. Students were encouraged to look through the reading this evening and to come to class prepared with questions to discuss during class tomorrow.
We worked through the remainder of the Lesson 8 worksheet today, tracing copper as it moved through the copper cycle and learning about the Law of Conservation of Mass in the Lesson 8 PowerPoint. We concluded the class with a demonstration. Most students were familiar with the chemical reaction of adding vinegar and baking soda together (it bubbles!). Students looked up the chemical formulas for both reagents and we discussed the products that are generated from combining the reactants (baking soda and vinegar). Students learned that the products of the reaction are sodium acetate, water, and carbon dioxide gas. The following question was posed: If a known amount of baking soda and vinegar were combined together in an open container on a scale, what would happen to the final mass of the products remaining in the container on the balance.
For the experiment, 5 grams of baking soda were added to 59.6 grams of household vinegar (5% acetic acid in water) in a flask placed on a digital balance. After a few minutes, the reactants stopped bubbling, and the mass of the remaining contents in the flask were found to be 57.5 grams. Therefore, the difference of 2.1 grams (59.6 grams minus 57.5 grams) should be the mass of the carbon dioxide gas released into the atmosphere. Tomorrow, students will conduct their own experiments and be tasked with using our available technology to evaluate the Law of Conservation of Mass for a given set of reactants.