This week, it was time to apply what we learned about biomolecules last week. We received a call for some detective help to analyze evidence left at the scene of a theft and the kids had to figure out who's lunch matched the food particles that were left by the thief. ![]() The groups discussed the information they had and worked on coming up with a plan that would let them narrow down the suspects. They ran the 4 tests we'd done last week on a sample of each person's lunch and then we determined which biomolecules were present in the foods as a class. ![]() After that, it was time to test the evidence samples. They ran the same tests on the unknown substance and we were able to make a match! It turned out that Bruce had left behind a little of his sunbutter and jelly sandwich when he stole Jerrel's iPod. ![]() This lab was a good opportunity for the students to practice setting up their own experiment and to see an application for the science in real life. Activities Have your child test for biomolecules in their foods one day. Glucose strips and iodine (to test for protein) are easy to find at a drugstore and biuret reagent (to test for starch) is available on Amazon. Fats can be found using a brown paper bag. General instructions for using these indicators can be found here. Review what types of foods have carbohydrates, fats, and protein and then have them make predictions before they test. See if their meal is a balance of all three.
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What makes up every living thing? Biomolecules! Specifically, we learned about carbohydrates, proteins (amino acids), and fats (lipids) this week. After a review of the scientific process and the basic facts about atoms and molecules that we've been working with this month, we watched a video on biomolecules to introduce todays topic (link below). Then, we were ready to do some discovery. Our lab groups were each given a set of food samples--vegetable oil, corn starch, glucose, egg white powder, water, and an unknown substance. They ran a series of tests, using different indicators, to determine which biomolecules were in each of these substances. They saw how iodine changes from brown to black when starch is present, or blue Biuret reagent reacts with protein and turns purple. They also saw how sometimes it can be hard to interpret results that aren't as clear or obvious as others, and how there can be other explanations for a result. We are learning as much about how scientist work as we are about the science itself. Precision is key! We will be doing a follow up activity next week, but here are a few other ideas if you want to learn a little more about biomolecules this week.
Videos: Amoeba Sisters Biomolecules Crash Course: Biological Molecules Bozeman Science: Carbohydrates Bozeman Science: Lipids Bozeman Science: Proteins Activities: Become an expert on the groups of biomolecules: link here Evaluate what you eat for a day. Look at labels, discuss which foods are made of each macromolecule. We literally are what we eat--our food was once alive, and all living things are made of the same building blocks, so we are made of the same things that our food is made of. This week was all about one of the most important substances for life on earth--water! We reviewed what an atom is and the polarity of the parts of an atom. Then, it was time to see what those negative electrons do in water molecules.
The students worked in groups and rotated between 6 different stations where they explored the shape of a water molecule and the properties of water that cause it to act in some surprising ways. They saw cohesion, the attraction of water molecules to one another, and adhesion, the attraction of water molecules to molecules of other substances, working while floating paper clips on the surface of a cup of water, counting how many drops of water they could fit on a penny, and tested how quickly water could defy gravity and travel up a strip of paper towel. They demonstrated that water in a solid state is denser than liquid water, and that water evaporates much more slowly than alcohol. They came home with a short assignment on how some of these experiments we did in class apply to water in the real world. I hope they have a few minutes this week to follow up and think about water in their life. Books: A Drop of Water--Beautiful pictures Videos: Properties of Water by Amoeba Sisters (We watched this in class.) What If You Stopped Drinking Water (for the kids who wondered why we were doing water experiments in Biology Class--just a quick look at one aspect of water's importance for life) Activities: Water Rotation Lab-- We did most of these experiments, but some would be fun to let the kids experiment with again, especially the demonstration of surface tension with the paper clips. Brainstorm all the ways you see water at work in the real world. What properties of water are at work? ![]() We started this week with 3 stations to experiment with atoms. All three stations involved static electricity, which is caused by the transfer of electrons from the atoms in one material to another. Ask the kids what happened when they put a charged balloon near a thin stream of water (I recommend doing this one at home--it's so fun! There is a link to all the activities below.) Next, we learned about the parts of an atom and then built a Lithium atom from candy and tooth picks & wood skewers.
![]() Then, we talked about the elements that make up all living things: mainly hydrogen, oxygen, carbon, and nitrogen. We will be digging into the compounds that these make in our bodies for the next 3 weeks, but for today, we just took a look at what those atoms look like. We discussed the balance of negative electrons and positive protons which keeps each atom neutrally charged. Then, they made their own paper plate models for each of the 4 main elements found in the human body. Follow up ideas:
Videos: Just How Small is an Atom? TED-Ed video that helps explain just how small atoms are. Parts of an Atom Further clarification for any kids who want to know more about electrons, neutrons, and protons. This Is Not What an Atom Looks Like Digs deeper into what atoms look like. Activities: Protons, Neutrons and Electrons Demonstrations We did some of these activities, but didn't get a chance to do them all, and this lesson will walk you through what is happening in more detail than I covered in class, if you want to do a follow up lesson. |
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May 2020
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