November Activities

It's been awhile since I last posted about what we are up to in biology class.  It has been a busy November- a lot has been going on, including my formal observation- but things haven't slowed down in class, so I want to give some updates about our activities this month.

We have been talking about chemistry and biochemistry lately.  Our study of chemistry began with matter, atoms, covalent and ionic bonding, and the Periodic Table.  We don't go into a lot of detail with these topics, but students do need a bit of background here before we move into biochemistry and discuss the macromolecules that organisms are made of.

We then spent some time talking about water.  While water is not an organism, it is a vital molecule to organisms.  We talked about how water's polar nature allows it to form hydrogen bonds, and this gives water several unique properties, including cohesion, adhesion, capillarity, high specific heat, and its ability to serve as a solvent for many other substances.  Students spent several days exploring the properties of water in a rotating lab station activity.  The first station showed students that a polar molecule like water will be attracted to static charges, while a nonpolar substance like oil will not be.  The second station had students comparing the dissolving ability of water and isopropyl alcohol for four different solutes.  In the third station, students used litmus and pH paper to discover the pH of several common solutions.  The fourth station had students explore the density of water in its solid form compared to its liquid form- the fact that liquid water is more dense than solid water is quite unique!  The fifth station had students playing with surface tension, the sixth station demonstrated capillarity, and the final station had students explore water's high specific heat.  Whew!!! It was a lot to get through, but I believe it was worth the time to give students a first-hand experience with the properties of water- rather than being abstract, they can see the properties at work and hopefully understand them better as a result.

Students measure room temperature for alcohol and water and then determine how long it takes each substance to change temperature when heated.

Students determine the pH of several common solutions.

Surface tension allows students to float a paper clip on top of the water- but you have to have a good technique to get it there!

Students attempted to dissolve four different solutes in water and alcohol- overall, water was a better solvent, although it could not dissolve sulfur!

After water, we moved on to the four major organic macromolecules in organisms- carbohydrates, lipids, proteins, and nucleic acids.  We discussed how each of these molecules is a large polymer made up of monomers joined together by covalent bonds.  We discussed how prefixes like mono (one), poly (many), and macro (large) can help us to more easily learn and use these words.  To introduce the macromolecules, students completed a group activity in which they worked together to try to identify elements, monomers, functions, examples, and pictures of each of the four different molecules.  After successfully making these identifications, students were given various short scenarios and had to relate each scenario to one of the macromolecules along with an explanation of why they chose that particular molecule.  Students then worked individually or in small groups to complete three different "Patient Case Studies," in which they assumed the role of a physician and were encountered with a patient with symptoms related to either carbohydrates, lipids, or proteins in their diets.  Students had to diagnose the patient, explain which type of molecule was involved and why, and develop a treatment plan- a revised diet- for the patient.  We followed up the case studies with a lab that allowed students to test for the various macromolecules found in foods.  More about that in the next post!

Student groups work to determine which type of macromolecule most closely relates to various scenarios.