I decided to teach chemistry as my first unit to my middle school science 7th-grade class. This year, my state switched to new science standards. Switching to this new approach has been challenging but I can see the benefits. Teaching middle school chemistry is one of my favorite parts of the year. My goal for my class is to have them make connections to chemistry in their daily lives.
There are a few fun activities that I think will help accomplish this. First, I want students to begin noticing chemical elements in the world around them. To do this, I will have students examine the nutrition facts of a box of cereal. Then, they will extract the iron using a magnet.
How can students find chemistry in everyday objects?
Start with something they eat. Have students read the nutrition facts on a cereal box, then extract the iron that fortifies it using a magnet. Once they crush the cereal and add warm water, tiny specks of iron collect on the bag. It makes an abstract subject suddenly concrete.
If you are interested in ready-to-use activities with teacher guides, answer keys, and fill-in-the-blank notes for your students, check out my Teachers Pay Teachers store. I have a unit to teach MS-PS1-1 as well as fun activities for every science standard!
Have you ever noticed how many elements are in most boxes of cereal? They are fortified with nutrients by the manufacturer. And even better, we can extract some of them using their chemical properties. The easiest one to extract is iron through magnetism. Try this lab with during your middle school chemistry unit!
To do this lab, you will need sealable plastic bags (sandwich-sized), a cereal with high iron content, strong magnets, and a blender. Here is the general procedure:
- Add cereal to a plastic bag and seal it.
- Ask students how they could remove the iron from cereal and guide them towards the answer (using a magnet).
- Have students run the magnet along the outside of the bag to see if they can remove any iron (they won’t be able to).
- Next, ask students why they couldn’t remove any iron (it is stuck inside the cereal). Ask them how we could make it easier to extract (break the cereal into smaller pieces).
- Then, have students break up the cereal. Tell them to be careful not to puncture the bag.
- Have students try again to collect iron on the side of the bag by running the magnet along the outside. Again, they should not be able to see any iron.
- Ask students what else they could do to make it easier to extract the iron (add warm water).
- After adding the water, repeat by running the magnet along the outside of the bag. This time, small specks of iron should begin to appear. If using a plastic cup, place the magnet on the outside of the cup and use a spoon to stir the liquid so iron collects near the magnet.
Helpful Tips: Use a blender to liquify the cereal. Be sure to add plenty of water as the cereal will thicken over time.
If students make small holes in the bag, have them pour the crushed cereal into a clear plastic bowl and then add water. This will prevent any leaks from the bag.
How do you teach modeling subatomic particles?
You can go two routes. Direct instruction walks students through reading a periodic table block to find protons, neutrons, and electrons using guided notes. Or let them explore PhET's atomic structure simulation and discover the patterns themselves. I find the simulation sticks better because students enjoy it and I can circulate.
I like teaching modeling protons, neutrons, and electrons in an atom during my middle school chemistry unit because it is an easy win for students. Plus, then they know what that “science thing” (meaning the atomic structure model) means when they see it out in the world. There are two ways to do this effectively.
Direct Instruction
You can teach students how to read a periodic table block, locate the atomic mass and atomic number, and translate that into the number of subatomic particles. When I use this approach, I use PowerPoint slides and guided notes to streamline the process. This helps when students ask, “How do I calculate the number of neutrons?” I can simply refer them back to their notes. Then, we practice with several elements on the periodic table.
Student Exploration
Another way to teach this to your middle school science class is using a model in which students discover the purpose of each particle. The best way I have seen to do this is using PhET’s atomic structure simulation. I begin by having students simply play with the simulation, learn its functionality, and begin to notice trends. I find this approach to work the best because students enjoy it and its lets me walk around and point out things while they focus on the simulation.
They will quickly discover that protons change the type of atom, neutrons affect the atom’s stability, and the charge changes. Using a guided lab helps steer them towards the learning objectives I want them to discover such as what the atomic mass tells them, the definition of ions and isotopes, and more. Plus, students really enjoy using these simulations. I find they remember the material more clearly when I use this method.
How do you teach counting atoms in molecules?
I use direct instruction: draw an atomic model of water, have students count the atoms, then introduce the rules for subscripts, coefficients, and parentheses. After that, it's practice, practice, practice. PhET's build-a-molecule simulation is a great exploratory companion because it names the molecules students construct.
Next, I teach students to decipher the composition of chemical formulas. Much like subatomic particles, there are two ways to do this – direct instruction or student exploration. I have only taught this subject with direct instruction and practice and have had success every year. However, I am considering changing to an explorative approach to see if it improves their abstract understanding of molecular structure.
Direct Instruction
Here is my general plan for teaching students to count the number of atoms in general formulas:
- Draw an atomic model of water to demonstrate how atoms (specifically, valence electrons) are being used to “connect” atoms together.
- Have students count the number and types of atoms in this model (2 Hydrogen, 1 Oxygen).
- Ask students how we could represent this using chemical symbols and then how we can simplify it.
- Look at several examples of common names and chemical formulas.
- Introduce the rules for counting atoms in molecules when there are subscripts, coefficients, and parentheses.
- Practice, practice, practice.
I think this skill does require a good deal of practice no matter how it is taught. I also like students having a set of notes for which to refer when they cannot remember how to read chemical formulas.
Student Exploration
I really love PhET labs for their value in student exploration – and they have an excellent simulation for building molecules. Students have buckets of atoms and connect them in different configurations. If they make a connection that is possible, the simulation will tell them the name. It really helps students make a connection between the physical model of an atom and the chemical formula.
Personally, I use both of these approaches during my middle school chemistry unit. I do some direct instruction first. Then, I let them explore using the simulation. Finally, we practice a lot to build their confidence in this skill.
What's a good hands-on lab for modeling molecules?
Marshmallows and toothpicks. Assign each marshmallow color to an atom type and use toothpicks as bonds. Tell students how many bonds each atom typically makes and let them build. It's a natural way to introduce double and triple bonds, since they'll find some molecules can't be built with single bonds alone.
Lastly, I like to return to a hands-on approach to understanding how we build physical models for molecules. An easy and fun lab involves students building models out of marshmallows of different colors and toothpicks.
Assign each marshmallow color as a type of atom. Use toothpicks to represent the bonds. Tell students how many bonds each atom typically makes and ask them to explore building possible combinations. This is a great way to introduce double and triple bonds as students discover they cannot build some molecules with only single bonds.
Chemistry is both an exciting and intimidating subject for middle school students. I think the challenge comes from its abstract nature. Atomic models, molecular structure, atomic bonds – students cannot see this happening in front of them. That is where modeling comes in. While modeling may not come naturally to your students, building this skill is an important step in their middle school career.
If you are interested in ready-to-teach units or fun review games, check out my Teachers Pay Teachers store for some great activities!