An updated version of this post is available at: https://inventorsoftomorrow.com/2016/12/05/states-of-matter-2/

A concept like “states of matter” may seem too abstract to teach to kids 3-7, but there are lots of hands-on ways they can experience the ideas, and then we just give them the words to connect these ideas together. They may mix the ideas around in their brains for a few days. You’ll hear them playing with the ideas. When they do, it’s easy to reinforce what they’ve got right, and add corrections as needed to  solidify their knowledge. (Read about my process of teaching my then 3-year-old about states of matter. At first, I thought he didn’t get it, but then observed how he processed the ideas over the next few days.)

Question of the Week: We try to organize each week’s lesson plan around a “question of the week” that is a summary of the key concept we are hoping to convey. Here are three possible questions for this theme: “How does water change when it’s very hot or very cold?” Or “Do things change when they change temperature?” Or “What’s different about water, ice, and steam and what’s the same?”

Opening Circle

Three states of water, hands-on: Pass around a cup with an ice cube in it. Ask them if they know what ice is made of (water). Have them touch the ice. Ask them to describe the ice – it’s cold, it’s hard. Ask if it changes shape if they pour it out of the container into their hand. Then pass around a cup of water. Ask them to describe it – cool, wet, liquid. Pour some from the cup onto a flat dish. Will it change shape? Hold up a plastic syringe and draw it open, filling the cylinder with air. Say “this container is full of something. What’s it full of? (Air) Can you see it?” Then place the tip of the syringe inside the cup of water and blow bubbles of air. Ask if they see the air now. Explain that the bubbles are gas (air) coming up through the liquid. Pull some water into the syringe: “now the container has water in it.” Squirt it back out so they can see that.

Ask them for other examples of solids. (Or you can hold objects up and ask if it’s a solid.) Ask them for other examples of liquids. (Optional: could demo how water moves/pours vs. how a thick liquid (like molasses) moves/pours.)

The container questions: Show kids a hollow container (like a vase). Ask if it’s a solid. Ask them what’s inside of it. They’ll say nothing. Explain that it’s filled with air/gas that expands to fill available space. Then fill with water/liquid. See how it flows out through the available space? Now, pour out the water, and put in some solids. Do they change shape to match the container? No – solids retain their shape.

Book: We used Matter: See It, Touch It, Taste It, Smell It by Stille. This is a preschool – first grade appropriate book that describes the basics about states of matter. We only read about half the pages in circle. (We used post-it  notes to easily find the pages we wanted to read.) Each page included “fun facts” for older readers, which we skipped in circle. Sample content: “Can you pour it? Does it spill? It must be a liquid…. You cannot hold a liquid. A liquid runs through your fingers.” (Small quibble – one of their examples of a solid is a glass window. There is some debate whether glass is a solid or a liquid.)

Activities to Explore States of Matter. We used many of these in class, but not all.

Ice melting: We filled Tupperware bowls with water and froze them overnight. In class, we put the ice in a tub. Next to it, we put a dish of coarse salt with a spoon, a container of water with eye droppers, and diluted liquid water colors with pipettes. (You could also offer wood mallets and kid-friendly chisels. You could offer a hair dryer, but take precautions so it won’t land in the water from the melted ice.) Kids dribbled on substances to melt the ice.

Challenge: Can you Save Captain America? Prep 24+ hours in advance: Fill a loaf pan halfway with water. Freeze it. Fill it the rest of the way with water. Take a Captain America figure, or any other toy, and drop him in – he’ll settle in the middle of the pan. Freeze it the rest of the way. In class, use it like the ice blocks, but kids have the extra motivation of trying to get the toy out of the ice.

Balloons: Containing Gas. We had balloons and balloon pumps. Kids could fill the balloons, and let go, and the escaping air (gas) propels the balloon. We also set up two tracks with balloon rockets: take a toilet paper tube, tape a balloon to it – you need to tape the balloon around the “neck” but you have to tape loosely enough that you’ll then be able to fit the balloon pump into the neck opening. Mount the tube on a string. Then kids can use the balloon pump to blow up the balloon. Let go and the balloon flies along the track.

Bubbles: Put out bubble solution and wands. As kids play, you can explain that the bubble solution is a liquid which holds together as we fill it with gas (the air from our lungs).

Water table: Have turkey basters and syringes that kids can fill with air (a gas) and put under the water, and use to blow bubbles. (Gas moving through a liquid.)

Tool of the Week: Thermometers. Have containers of water at varying temperatures. Kids use their hands to guess what is the warmest and what is the coldest, then measure with a thermometer. Works better for the older kids with a good grasp of numbers (so they understand that 72 is warmer than 48).

Surface tension: Put out pennies, pipettes, and water. Challenge the kids to see how many drops of water they can put on a penny. The first 10 or so drops just puddle out to fill the penny, but after that, it starts creating a dome of water. The bigger the dome, the slower you have to work, because each time you add a drop, the whole dome shivers and re-aligns itself. Our record was 30 drops of water! Note, the pipettes required a lot of fine motor skill to manage one drop at a time – our 6 and 7-year-olds could do it. An eye dropper might be easier for younger hands to control.

Experiments with dry ice: Dry ice is unique because as it warms, it sublimates – goes directly from solid to gas. There are lots of fun ways to play with dry ice… see http://gooddayswithkids.com/2014/09/10/fun-with-dry-ice/

Evaporation experiment: This is a good take-home exercise, or good if you are in the classroom several days a week. (We’re only in our classroom once a week.) Students mix a spoonful of salt into a small amount of warm water. Then use an eyedropper to add a few drops of liquid color and mix it up. The salt “disappears”. They will then leave the container of liquid on one of the windowsills. Over the next few days, students can check the container to see if the water evaporated, leaving behind the salt and color.

Grow crystals: Again, if you have time, you could make rock candy or Epsom salt crystals. With these experiments, you dissolve a solid into a liquid, then as the liquid evaporates, the solids gather into crystals. Learn how at the Science of Cooking or Kidz World.

Volume comparison: We wanted to do an exercise where kids could see how liquid flows to fill a space versus how solids hold their shape, leaving gaps between them. We tried having measuring cups, water, and plastic bears and measuring them into containers, but it ended up not being an effective illustration of the idea. (Though the little ones had plenty of fun scooping up plastic bears and floating them in containers of water.)

Mixing Colors: Have children use liquid colors (e.g. tempera paint) and mix colors in a painting – red and yellow make orange. Then have them use solid colors (crayons, pastels or chalk). Instead of orange, you end up with red scribbles with yellow scribbles laid over the top of them. The solids do not mix as well.

Outside time: It happened to be below freezing the day we had this class. (Not typical for Seattle, even in January.) So, we went outside, and found that lots of the sandbox buckets and scoops were filled with ice. We used warm water to loosen it, broke the ice free, then had fun breaking ice into bits.

More activity ideas (and ways to explain states of matter) at Mommy Lessons 101.

Class Projects

In our morning class, we made “oobleck” aka “non Newtonian fluid” aka “Not liquid, not solid.”  This involves mixing water and cornstarch. It creates a unique substance. If you pick it up in your hands, you can roll it around and make a solid ball, but when you stop moving your hands, it melts into liquid and dribbles out of your hand. You can stir it slowly like a liquid, but if you smack it with the spoon, it acts like a hard solid. Learn more, and find recipes at Steve Spangler Science and SciFun.

In our afternoon class, we made Flubber. [Should not be eaten! Don’t use if you have kids likely to eat it.] Mix 3/4 cup warm water, 1 cup white glue or clear Elmer’s glue. In separate container, mix 1/2 cup of warm water and 2 teaspoons of Borax (can find in the laundry aisle at the grocery store. DON’T use boric acid which is a pesticide and very toxic. Just because the name is similar doesn’t mean it’s the same thing!!). Then combine the two mixtures. Knead. Drain excess water. Put in sensory table or tub and let kids play.

Store in baggies. If it dries out at all, just rework in some warm water to get back to the right consistency.  (Source: Explore! Ice Worlds which also has a great lesson plan for turning this simple flubber exploration into a full experiment on the movement of glaciers.)

Other recipes for similar substances:

• Not liquid or solid. 1 cup cornstarch, one cup baking soda. 1/2 cup of water. Mix. it will harden, then soften… will drip from your hands.
• Gak: 1 cup Elmer’s glue and 1 cup liquid starch. Add starch to glue slowly, mixing it in with a spoon then kneading it as it thickens.

This post explains the science of polymers: http://www.stevespanglerscience.com/lab/experiments/glue-borax-gak/

Art Exploration

Epsom salt painting: We had a dish of Epsom salts and a dish of warm water. We mixed in the solid salt into the liquid water – it appeared to disappear. Then we painted with the water. As the water evaporates, the salt crystals reappear.

Painting with glue: We mixed liquid watercolor in with Elmer’s glue. Kids painted with it. As the liquid evaporates, the glue turns into a solid.

Watercolor resist: We used crayons (a solid) to draw. Then painted watercolors (a liquid) on them. (Sorry for the low quality photos this week – I forgot to take many pictures!)

Science Demos: We had a couple experiments to do that required very close adult supervision to avoid steam burns, so we did those as demonstrations during snack time when all the kids were seated. If you’re working with just one or two kids, they could easily participate with appropriate caution.

Changing states with heat: have a hot plate, small pot (clear glass would be great), and ice. Show the children the ice, explain that it is water in solid form. Put it in the pot – ask what will happen as you heat it. Show how as it heats, it turns to liquid. Continue to heat. As the steam starts to rise and they can see it, ask them what the steam is – it’s water in gas form (although to be really technical, gas is invisible… what we see that we call steam is tiny suspended drops of water) Ask what would happen if we turn off the heat and let it cool down. Ask what would happen if we put the pot in the freezer.

Teach vocabulary as you do the demo: melting, boiling, evaporation, freezing. If you have readers in your group who love big words, you could print a poster of this graphic, from www.ck12.org  (This site also has a good description of key concepts of states of matter.)

We used a closed electric kettle for this demo, which releases steam in a concentrated location, which allowed us to demonstrate condensation as well:

Condensation – gather gas and observe as it changes to liquid: As the water boils, ask the child to watch for steam (gas). As soon as they see it, they hold a clear plastic cup upside down over the spout. (With close supervision!) When the kettle switches off, count to five, then turn the cup over and look inside. What do you see? (Liquid water.) Explain that as the steam cools, it turns back to water.

The microwave demo: Take a quart size freezer bag, Ziploc style. Ask a child to put in a few ice cubes – solid water – seal it well. Ask them what happens when you put things in the microwave – they get hot. Put it in the microwave for one minute. What’s happened to the ice – probably partially melted, part still ice. Have them touch the outside of the bag to see what temperature it is. Still cold. Put it in for another minute or so. Now it’s all liquid – touch the bag (VERY carefully at first to test temperature!!) – now it’s hot. Tell the kids that’s the last time they’re allowed to touch the bag. Heat it then in 20 second intervals – you’ll see the bag inflating like a balloon. Explain that is the liquid water turning into gas and expanding. You can take it out of the microwave when it’s expanded (carefully!!) and show how quickly it deflates as it cools. Do NOT open the baggie of steam, and DON’T let them touch it. If you run the microwave long enough, and there’s enough steam, it will pop the bag open. I don’t really recommend this, but it happened to us, and didn’t make a mess…

Clouds: Show pictures of the same location on a clear blue-sky day, on a partly cloudy day and on a rainy day. Discuss how clouds are water vapor. Discuss how they form [evaporation] and what causes the rain to start. You could do water cycle in detail unless you’ll do this in another session of class. If there has been frost recently, you can share with the children that this is when the water vapor in the air (gas) gets so cool that it first turns to liquid (dew), and then freezes into a solid (frost).

Closing Circle Time

Matter: Talk about matter and how everything that they can see, hear, touch, smell, or taste is made of matter. Explain that matter comes in three forms: solid, liquid, gas. (We’re not going to get into plasma with this age group.) Explain that matter is composed of molecules – very tiny pieces.

Duplo molecules: Assemble together about 10 duplos. Put them in a tray or pan. Tell the kids that we’re pretending they’re molecules, but remind them that real molecules are too small to see. Say that this is a solid – all the molecules are very tightly bonded together. Slide it around in the tray – it retains its shape. Then we’re going to pretend to heat it up (Add energy.) The molecules start getting excited. They loosen their bonds and drift further apart. (Break the duplos apart.) See how it flows across the bottom of the tray, filling it up like a liquid? Then we heat it more. (Add more energy – molecules get more excited.) Shake tray till duplos start flying out – the gas is dissipating around the room.

Note: This would be even better done inside a clear box with a lid. When you got to the gas portion, you could show how the molecules dance around, but stay inside the sealed container. Then take off the lid, and show how if gas is in an open container, it can escape and mix with other gas molecules.

Solid, Liquid, Gas game: During closing circle for the older kids, we played an active game. If we called out “solid”, they grab hands with the people close to them, lock their elbows and freeze in place. If we call “liquid”, they still held hands, but can keep moving and flowing around the room. If we say “gas”, they let go and move away from each other to fill the space. This could a movement game, or it could also be done to music as a “states of matter dance party.”

This kinesthetic game really reinforced the learning for the kids. Three days later, I listened to my 5-year-old describe states of matter to his preschool teacher. As he described each, he was moving just like we did in this game.

Snack – Make Your Own Ice Cream  **I have not play-tested this yet.**

Supplies: Small Ziploc bags. (Sandwich size is big enough, but the quart size comes in freezer bag style – the freezer bags are sturdier). Optional tape. Gallon size Ziploc bags. Half-and-half, vanilla, sugar, salt or rock salt, ice cubes or crushed ice, spoons, gloves or washcloths. (Quantity depends on how many kids will be making ice cream – the directions below are for one child’s serving.)  Recipe and directions written in kid-friendly language to be placed on table. (laminating these will help them survive better)

1. In small Ziploc bag, mix the following (Older kids can measure their own ingredients, younger children will need help.)

• 1/2 cup of half and half
• 1/2 teaspoon vanilla
• 1 – 2 tablespoons sugar

2. Seal small bag – it’s important to squeeze all the extra air out! Tape the bag closed OR place inside a quart size Ziploc.
3. In a gallon size Ziploc, put several ice cubes or scoops of crushed ice and about 3 tablespoons of salt or rock salt*. It should be filled about halfway.
4. Put small bag inside big bag, nestled down into the ice.
5. Seal the big bag – it’s important to squeeze all the extra air out!
6. Give kids gloves or a washcloth to wrap bag in. Then have them shake and/or rub the bag for five or more minutes till the milk mixture is slushy. (liquid turns to solid!)
7. Remove little bag from big one. Wipe the salt off the top of the little bag before opening.
8. Give kids a spoon and let them eat ice cream out of the bag.

Explain to the older kids why we use the salt: The salt lowers the freezing point of water from 32 degrees to 20 degrees or less. This very-cold ice makes an environment where the ice cream can freeze.

To learn more about the science of this snack, see “Ice Cream in a Bag Lesson Plan.”

Optional Preview/Review: You may send a link to a video to parents before class that they can preview with their child to set up the week’s activity, or it could be sent as a follow-up. Here are some options:

Matter Chatter Song: https://www.youtube.com/watch?v=C33WdI64FiY

States of Matter for Kids: www.youtube.com/watch?v=wclY8F-UoTE (better for older kids)

This video has a few interactive games as follow-ups: http://www.science4us.com/elementary-physical-science/matter/states-of-matter/

Books

Change It!: Solids Liquids Gases and You by Mason. Age 4 – 7. Each state is introduced with a brief description, everyday examples, and a challenge – “can you find three more solid objects in this picture?” There is also a simple activity for each state. (Making play-dough for solids, putting water in different shaped containers for liquids, etc. Good.

What Is a Solid? by Boothroyd.(Also has a Liquid and a Gas book.) This would be a fine series to read with ages 3-5. Simple words, familiar examples, pictures are fine.

What Is a Solid? by Peppas. (Also has a Liquid and a Gas book.) For first grade and up. Good descriptions, engaging photos, “what do you think?” sidebars on every page that encourage kids to make their own observations and try their own experiments. Good, just too advanced for many of our students.

Splat!: Wile E. Coyote Experiments with States of Matter by Slade. This is aimed at 3rd-5th graders, but my five-year-old loves it because of the Wile E. Coyote theme. I certainly wouldn’t use it in a group of 3 to 6-year-olds, but it works one on one if the young child is interested in it and you can stop to explain and give more details.

What Are Solids, Liquids, and Gases? by Spilsbury. 4th grade and up.
Solids, Liquids, and Gases by Stille. 4th grade and up.
States of Matter by Mullins.
Way over the head of our students. Of the three, I like Spilsbury best. But, even though you wouldn’t read these to young kids, they might still be useful to YOU. General hint for those of you are feeling uncertain of your grasp of science concepts: if you’ll be teaching preschool age kids, it may be really helpful to you to read a 4th grade level book to yourself in advance. It explains the concepts at a slightly higher level than what you’ll be covering in class, which means if kids have questions, it can help you to answer them.

Experiments with States of Matter, by Cook. Has good directions for some classic experiments, not all of which have any direct relation to states of matter: baking soda and vinegar volcano, chromatography, invisible ink, etc.

Material World the Science of Matter by Jay Hawkins (non-fiction, has some nice descriptions of activities, nice photos, the activities are mostly too complex for our class, some of the info is a bit advanced)