I'd like to preface this post with, not every lesson I do is "fun." There are a lot of activities on this site that are hands-on, interactive, and contain some novelty but not every lesson I do, everyday, is that way. Here is one of those lessons.
Our students take their first year of biology as 9th graders, before they ever get to chemistry. This tends to make our biomolecules unit a bit more difficult. Students have some understanding of chemistry concepts, like bonding, neutrons, electrons, etc, but not extensive knowledge. Before we deep dive into carbohydrates, proteins, lipids, and nucleic acids, I like to discuss the role of carbon and functional groups. Then I generically go over the terms monomers, polymers, dehydration synthesis, and hydrolysis.
Properties of Carbon and Functional Groups
For this part of the lesson, I use a video, direct instruction, and students take hand-written notes. Students take hand-written notes, along with me using a document camera, for most information. I tend to move too quickly through traditional slides notes and so writing the notes along with the students works really well. Many of them even say they like it (shocking!) because they find the process relaxing. It helps me slow down, have discussions, and give kids time to process. This does mean it takes a bit longer than fill-in-the-blank notes or giving out teacher generated notes.
First, I start out with this short video from Professor Dave.
Then, through direct instruction we take notes on the Properties of Carbon. Here are what my notes look like. I have posted some notes in the picture (pink) so you can see some of the questions or discussions we might have as we write the notes.
In honors, we go a bit further and discuss functional groups, our on level classes usually will skip this section and move on to monomers and polymers. We do this, for a few reasons.
When students complete dehydration synthesis models and activities, knowing the functional groups help them determine where the water is removed in the reaction.
Knowing functional groups also helps students identify biomolecules using their chemical structures. For example, in proteins, knowing what the amino group looks like, they can identify amino acids quickly.
Students and I write out the 5 functional groups (hydroxyl, carboxyl, amino, phosphate, and carbonyl). I outline the groups and we list out which biomolecules they are found in. Here are what my notes look like.
After that, students practice by highlighting functional groups on worksheet with assorted biomolecule structures. They don't understand the whole structures, yet, but they can begin to get comfortable with looking at the structures and finding the functional groups within them.
Let them struggle with the work for a few minutes before jumping into save the day. Here are some key things that will confuse them:
Some of the ring structures do not have the "C" present. The carbon is assumed where the lines meet. Most of them won't know this but they can use some of the other diagrams to figure it out, you may need to give them a hint.
When looking at a structure made of multiple parts, dehydration synthesis has occurred. There may be an O- instead of OH (phosphate groups) because that hydrogen was lost (losing a +, makes it -).
NH2 will be written in this form instead of N-H-H form, like you drew. Some get this connection and some don't.
Here is the worksheet. I give them to the end of class to work on the worksheet. They can work with a partner. They put it in their notebooks and we go over the misconceptions and answers at the start of the next period. The answers don't just include what is highlighted, but I also have them try to guess which type of molecule is which biomolecule, and have them look for any patterns. This helps later on when we get to the specifics of each biomolecule.
I hope this was helpful! Happy Teaching!
Mrs. Townsend