Past projects 3
Sensors and Scales
Funded Oct 19, 2017Thank you so much for funding my classroom project, "Sensors and Scales". I received the materials just as my Chemistry students were starting their final stoichiometry project. For this project, I gave students the reactants and products for a chemical reaction that produces a gas, along with the size of a balloon they need to inflate. Students balanced their chemical equation and calculated the volume of the balloon, then used stoichiometry to figure out how much of the reactants they need to mix together to blow up the balloon. The final assessment came when they actually did the lab and I measured the final size of their balloon.
One of the first things they need to do in this lab was calculate the number of moles of gas involved. For this, they needed to use the ideal gas law, PV=nRT. Prior to this year, I had to tell students to "assume the pressure is 1.0 atm". However, this year students were able to measure the pressure in the room themselves, using the pressure sensors! It came out to be 0.97 atm. While this didn't change students' calculations significantly, it was an important step to think of air pressure as something that is measured and can vary.
They also used the scale in this lab when they were measuring the solids needed for the chemical reaction. Being able to measure to two decimals (exp: 0.53 g) instead of one (0.5 g) is an important distinction that allowed them to be more precise. Although it is less important for this lab, we definitely have labs coming up where this precision will be truly necessary!
Meanwhile, some of my Biology students were busy conducting a lab in which they tested the effect of pH on enzyme activity. Without the pH sensor, this lab wouldn't have been viable. With the sensor, this student-proposed question was able to be answered! Students discovered that yeast were most effective at breaking down H2O2 (hydrogen peroxide) at near-neutral pH's. When pH was very acidic or very basic, the reaction did not go as fast. Fun fact: they used the pH sensor to check pH, and they used an oxygen sensor from another Donor's Choose project to measure reaction rate.
I've always done a lot of labs in my classes, so having these sensors didn't change my class in an obvious, dramatic way. However, just because something is not dramatic does not mean that it is not impactful! Having these sensors simply means that I am able to do better labs – labs that work more seamlessly, labs where students are able to collect better, more accurate data. For example, I am really excited to use the gas pressure sensors to update a current problematic lab that uses syringes to measure the effect of temperature on volume/pressure.
Lastly, a story: directly across the street from our school is a Chevron gas station. It is the place students go for snacks before/after school and during off campus lunch. So when I told my students that these sensors were donated by Chevron, they were extra excited.
Thank you for helping make learning magic!”
With gratitude,
Ms. Matell
Quantifying Gas Production With Carbon Dioxide and Oxygen Sensors
Funded Aug 24, 2017Last year, the labs my Biology classes did to study photosynthesis and cellular respiration were uniformly frustrating. This year, through your generous support, students were able to actually measure how photosynthesis and cellular respiration result in changes to the amount of oxygen and carbon dioxide. One student summarized it this way: "Without these sensors, we would have either done labs that didn't really work, or we would have only been able to learn about it from a textbook."
All of my Biology students had a chance to use these sensors in either a photosynthesis or cellular respiration lab. Each group picked a lab that tested one of these two processes, and also picked a sensor to use. One of the coolest parts was seeing how some groups of students chose to use oxygen sensors and others carbon dioxide sensors (for the same lab). Before I would release the sensors to each group, they had to explain what results they expected to see, why, and what results they would expect if they were using the other sensor.
After doing the labs, all groups wrote Claim-Evidence-Reasoning paragraphs based on their data, and then presented their results to the class. For example, one group suggested that "Photosynthesis works best at room temperature and does not work very well at very cold or very hot temperatures." They were able to back this up with graphs showing how, when exposed to light, spinach leaves that had previously been doing cellular respiration gradually switched to photosynthesis (beginning to increase rather than decrease oxygen levels), but this process happened much slower at hot and cold temperatures.
In addition to this main lab, students used the sensor to reassure themselves that yes, they breathe out carbon dioxide and breathe in oxygen. Some students also chose to use the sensors to measure enzyme reaction rate as part of a unit project.
When products are a gas, it can be really hard to visualize what is happening. These sensors allow students to really SEE and quantify what is happening. This is particularly useful for kids who have a less abstract view of the world, or who (as good scientists) don't simply trust what what they are told.
Thanks for your generous support! Without you, we would not have these sensors.”
With gratitude,
Ms. Matell
This classroom project was brought to life by Tom's of Maine and 9 other donors.Exploring Genetics: Genotype and Phenotype
Funded Oct 24, 2016Thank you so much for your support of my classroom! I didn't upload this letter right away because I wanted to wait until I was teaching the genetics unit and actually got to use the material with the students.
Last semester, we had studied DNA: structure, replication, transcription, and translation, and we also looked at cellular replication. Coming back from break, the DNA electrophoresis kit really helped remind the students of what we had studied before and get them ready for the genetics unit that is coming up. I do a lot of labs, but the students really liked this one because it felt "real". One student noted, "Wow, now I understand what they are doing when they DNA test on CSI!" Another student, just joining our school, didn't have much background knowledge about DNA. By the time we were done with this project, she could give a basic description about what DNA is and why it is important as well as explain how the gel electrophoresis works to distinguish between individuals.
Then last week, we started the full genetics unit by counting different colored/shaped kernels on the corn cobs. Through the next few weeks, we will be using this data to come up with an explanation of how dominant and recessive traits are passed through generations. Before doing the lab, we studied a bit about the life cycle of corn. Students were interested to find out that corn is really a fruit, and that each individual kernel is a genetically distinct individual. After doing the counts of the purple/yellow and sweet/starchy cobs, our compiled data turned out to be amazingly consistent – with about 1000 kernels per count, we got perfect 3:1 ratios in both cases. This will be very helpful to students when it comes time to analyze data.
I firmly believe that learning science happens mostly through the process of doing it. The analytical skills students gain are applicable to a wide variety of future careers. Plus, students actually learn and retain content better too! Your donation of the electrophoresis and corn supplies filled in a hole in our Life Science curriculum where I didn't previously have many opportunities for labs. It's been great to be able to see students encounter this unit hands on, and I'm excited to see their final analyzes in a few weeks. Please walk away knowing that you have impacted the science education of my students this year and in future years!”
With gratitude,
Ms. Matell