States of matter can be a tricky topic to broach with young students. My students quickly attach to solids and liquids, but gas isn’t apparent, and phase changes are confusing. There are many scientific inquiry activities out there to explore phases. Combine science learning with some math activities and reading, and all of a sudden you have integrated lessons that make learning stick. These are a few of my class's favorites:
I showed students a few objects: stapler, bottle of water and filled balloon, and asked them to tell me the differences between them. Once we got past simple physical attributes, students were able to figure out that some things were hard and others were liquid. They also knew the balloon was filled with air. We then watched a Brain Pop Jr. video to explain more about solids, liquids, and gasses. Throughout the week we used several online movie resources to further explain learning as we explored with hands on activities, like StudyJams! A few of our other favorites were Bill Nye the Science Guy’s "States of Matter" and "Changing States of Matter" by Southeast Water.
After learning what states of matter are, I asked students how we might create a snowman without any snow (which is easy to imagine since we rarely, if ever, have snow here). The idea excited them, but their suggestions revolved around reshaping ice. I showed the class three balloons of various sizes. Eventually they decided that filling the balloons with liquid and freezing them might make the three balls we needed. Placing the balloons in the freezer with a plate or book on top can help make a flat surface so that the snowman is more stable.
To assemble the snowman, unwrap the ice balls from the balloons and add salt, which helps the ice stick together. (Older students can learn about salt’s ability to melt ice.) Place the snowman in a bucket so that as he melts, you don't have water running all over. I cut decorations from felt. You can dress and decorate the snowman when you add the salt.
Every two hours (or as the school day allowed) we recorded the snowman’s height, the water level in the bucket, and the time of each observation on the whiteboard. Students recorded what they saw in a little booklet. We discussed how the snowman started off as a liquid and turned solid in the freezer, but then melted back into a liquid. Due to extremely low temperatures, our snowman survived most of the day. You can also practice prediction, determining when parts will fall, and what will happen next. Most students didn’t guess that the head would topple first!
After our snowman melted, we made predictions about how long it would take him to evaporate. Unlike rainwater soaking into the ground, students had to commit to the idea that the bucket of water was “disappearing.” Another option is to put the water in a crockpot and heat to see steam form. A neighboring class put the snowman back in the freezer to see if he would reform, but learned that liquid always takes the shape of its container.
Conclude with writing about the states of matter and the life cycle of a snowman. My students used their information to make an EduCreation that explained what happened to the snowman as he went through different states of matter. Our QR codes linking to EduCreations hang in the hallway along with our Snowman Construction Company and snowmen that we measured using nonstandard units.
One fun thing about phases of matter is how different mixtures and solutions can yield different results. Students experienced this firsthand by making different play substances from solids and liquids. First, students combined cornstarch and conditioner to make a simple, smelly play dough. They were able to identify the solid cornstarch, and there was some discussion about a powder behaving more like a liquid. Then students saw that they couldn’t undo the creation, learning about the permanent nature of solutions.
Next, we combined cornstarch and a small amount of water. The result is a very unusual plasma. The Gak, as we call it, looks like a liquid and will slowly leak and pour like a liquid. Scooping up the substance makes it behave like a solid that can be formed into a ball, cut with a knife, or broken into pieces. At rest, the goo slides back together. Technically, the material is a “non-Newton liquid” due to varying pressure of cornstarch grains, but really? We just think it’s fun. Check out Dirtmeister’s Science Lab for more details on this sticky stuff.
Teacher tip: warm water will clean most of this up, and dry cornstarch mix brushes away easily.
Once students know the basics, it’s time for real fun. We made snowmen out of pipe cleaners and suspended them in Borax dissolved in water. Three tablespoons of Borax to one cup of water works well, but I usually mix an entire tub. Suspend the pipe cleaners overnight and you will have crystals formed by morning. The crystals are hard and can be removed from the water. They retain their new, solid form. Students are amazed to see a liquid form a solid without the freezer, and the payoff is way quicker than waiting for rock candy to grow.
Now that students are expecting simple solid and liquid phase changes, we step it up and talk about gas. One discovery is that gas actually has weight. We start by comparing helium balloons with air-blown balloons and note why they act differently. Most students can identify the contents of the balloons and start to understand gasses. Next, make a balance with paper bags on each end. Combine vinegar and baking soda to make a bubbling gas. You can “pour” the invisible gas into one of the bags causing the scale to move. It amazes the students, but gas really is in the air!
Take a trip outside with Mentos and a full-sugared soda. Use a paper tube to help drop all the Mentos into the soda at once and back up quickly. The reaction of the candy and soda will release gasses all at once, throwing soda high into the air. The reaction is quick, but students can see the power of a gas release.
Finally, find old film canisters with snap-on lids. The clear kind with a lid that slips inside the tube works best. Put water in the canister. Add an Alka-Seltzer tablet, quickly snap on the lid, and put it face down on the ground. Back away and wait. Within 30 seconds, the gas pressure will build inside the can and cause the bottom to rocket high into the sky. This is rather powerful, so make sure you are outside with plenty of space and resist the urge to go stand over the cup before it blows. Students can see how the remaining tablet is still fizzing on the ground and are able to understand how gas is released.
We enjoyed reading about changes in matter through Snowballs by Lois Ehlert, and then making our own snowmen out of found objects. Students recorded phases they noticed at home, including steam coming from cooking foods and water vapor recollecting as water droplets above the stove. As we move into our weather unit, understanding how water is able to change will lead into making water cycle bags where we can witness water moving through the different stages inside a plastic bag affixed to the class window.
It doesn’t take much to amaze and mystify with simple science. Making lessons hands-on and meaningful, plus a little winter magic, engages students long after science class is over.
What other fun ways do you bring states of matter to life in your classroom?