[An updated version of this post is at: https://inventorsoftomorrow.com/2016/12/22/chemical-reactions-for-kids/, but it does not include all the experiments in this post, so read them both. 🙂 )
During our Chemistry unit, we did States of Matter, then Mixtures, then Reactions, and now Dramatic Reactions. At the beginning of the year, I’d written a flyer for our Family Inventors’ Lab, which said amongst the activities it listed, that we would “make things go boom.” And this was the week to fulfill that promise!
We began with 20 minutes of gathering time, where we had just some simple activities inside: invisible ink with lemon juice and melted crayon drawings, Magna-Tiles and Slot-Together Translucent Builders (aka Crystal Climbers.)
You shape these rockets around a film canister, but then you can take the film canister out. You CAN use these rockets for the film canister rocket launch I describe below. I don’t recommend it, because a) it makes it harder to fill and seal the canister for the launch, b) with the paper rocket, the canister will only launch about 6 – 12 inches into the air instead of 6 – 12 feet, and c) using it this way pretty much ruins your lovely little paper rocket – they end up wet and crumpled. (You could fix issues c by making rockets out of craft foam, and they could be infinitely re-useable.)
We sang “boom chicka boom“, an easy and fun call and response, that tied into our theme of making things go boom.
We reminded them of two weeks ago when we mixed materials together, and some mixed and some stayed separate we reminded them that last week we talked about reactions – how when you mix two things together, they react (make noise, fizz, change temperature, etc.) and that it changes them. We told them that this week we’re going to go outside, and use chemical reactions to “make things go boom.”
Demos and Experiments Outdoors
Film canister rockets: http://imaginationstationtoledo.org/content/2010/08/film-canister-rockets-2/ First, you need film canisters. (It’s best to use the style used for Fuji 35 mm film. where the cap fits down into the canister instead of like a Tupperware lid like the Kodak ones do.) If you don’t happen to have a stack of these almost-obsolete items sitting around, you can easily order them from Amazon or elsewhere. Break Alka-Seltzer tablets up into quarters. Fill the canister halfway with water. Drop in two quarter-tablets. Seal the canister. Flip it upside down so it’s resting on its lid. Back away. As soon as enough pressure builds, the canister will blow off the lid, launching up to 20 feet in the air with a great popping sound! (This MUST be done outside.)
It takes about 15 – 20 seconds on average. If you want the reaction to be quicker, then after you put on the lid, give the container a little shake before you set it down. We had adults actively leading this – see my notes on group process later in the post.
Math extensions: Measure how far away the canister lands. (Have a long tape measure! Ours landed 10 – 15 feet from where they were launched.) Count how many seconds it takes for one to pop. Try adjusting variables such as using just one quarter tablet and three quarter tablets to see how many seconds that takes.
Note: If you don’t have alka-seltzer, try it with a tablespoon of vinegar and 1/2 teaspoon of baking soda: http://ecscienceactivities.blogspot.com/2009/02/kindergarten-chemistry_19.html
Exploding paint bombs. Take a film canister. Put in a water-based paint (we used tempera mixed half and half with water). Add an alka-seltzer tablet. Seal. Shake a bit. Set down upside down on a piece of paper. Move away! http://kidsactivitiesblog.com/75017/exploding-paint-bombs-activity; www.housingaforest.com/exploding-art/
Note: this could make a very big mess. Since we meet in a public park, we wanted to contain our mess more, so we were so glad to come across this YouTube video www.youtube.com/watch?v=bfNpNTXuWMc which demonstrates how to contain this experiment inside a plastic tub (so it can even be done indoors.). It’s also lots of fun because the containers go off gradually over a long and unpredictable period of time, and each makes the pop when it launches, then a loud THUNK when it hits the top of the tub! We did this one as a demo, not hands-on for the kids.
- Take one quarter of a paper towel. Put 1.5 tablespoons of baking soda in the middle of it. Fold it into a packet that holds all the baking soda. Set aside.
- Put ¼ cup of water and ½ cup white distilled vinegar into a Ziploc brand sandwich-size baggie. Seal it most of the way.
- Now, working very quickly… put baking soda bundle into the baggie. Zip it closed. Toss it aside. Start counting till it explodes. It will take 20 – 30 seconds, unless you shake it first – the more you shake it, the quicker it goes. When you do the film canister rockets, it can be hard to tell exactly when they’ll pop. The fun thing about the Ziplocs is they build anticipation as the kids see the bag swell, and swell more, until it’s bulging and straining, then it starts rocking, then it blows.
We did have all the kids make their own time bombs. with lots of adult support. See notes below on group process.
Notes from our experimentation: Quantities matter a lot. We tried to find ways to reduce the amount of vinegar to reduce cost / supply use, but you really need this much. Bag choice matters: we tried using non-Ziploc brand baggies – we discovered that all the bags (or at least the five we tested) all had a minor manufacturing defect which meant they weren’t quite air-tight. Would be fine for bagging a sandwich, but doesn’t work at all with this experiment as the pressure couldn’t build enough to blow. We tried using snack size baggies – just not enough room to work in. We tried using quart size freezer bags. They’re a little too sturdy and you would have to increase your ingredients to use even more. What you wrap the baking soda in matters – Kleenex and fast-food napkins both melt into this nasty shredded pile that leaves a mess that’s hard to clean up – the paper towels stay more intact, so easier to clean up. (Note, we gathered up the bags, poured as much of the liquid down the drain as possible – not on the lawn, and threw away the baggies and paper towels. You could do this inside – I’d toss the bags onto a oil drip pan or into a sensory bin to contain the liquid that blows out of them.)
Tool of the week option: use a thermometer to check water temperature.
Although this seems like it would be a huge mess, it’s actually an easy clean up IF you set the bottle inside a cake pan or plastic tub so it contains it all.
- In one container, mix 1 package of dry yeast and 4 tbsp of warm water (it needs to be between 100 – 110. If it’s colder, it won’t wake the yeast, if it’s hotter, it kills it. We explained this to the kids, describing the yeast as “little tiny bugs” that we’re waking up. They all got the idea. But one tender-hearted child then worried about whether our experiment would be hard on these little bugs…)
- Then tell a story about an imaginary elephant who needs to brush his teeth, and say you need to make a bunch of pretend toothpaste. (i.e. stall for a few minutes while yeast activates)
- Put an empty soda or water bottle on a tray (we used a 1 liter Dasani water bottle). Add 1/4 to 1/2 cup hydrogen peroxide (note: it’s gotta be the strong type you can get from beauty supplies, not the weaker 3% concentration you find in the grocery store. In a beauty supply store, it’s called “clear developer“. You’re looking for volume 20 which is 6% hydrogen peroxide.)
- To the hydrogen peroxide, add about 10 – 15 drops of food coloring. Then add a couple big squirts of dishwashing detergent. Swirl to mix the contents.
- Set bottle of peroxide mix into tray. Pour yeast water into bottle. Step back!
- It oozes and oozes and keeps on oozing.
- After explosion / extrusion, feel the bottle – it’s warm. Exothermic reaction.
- We did just one batch of this per class as a demo, not hands-on.
Mentos and Diet Coke: We ended with this outdoors-only demo. Many of our older kids (5 – 7 year olds) have see YouTube videos of this. Either very simple demos, or amazingly intricate Mentos fountains. We had 20 ounce bottles of diet coke. I opened one, tried to drop in three Mentos – as soon as the first two hit, it exploded, so number three got blown right out – geyser went up maybe 12 inches? Then I used this Geyser Tube, loaded with 6 Mentos. When we pulled the launcher, the geyser only lasted for a few seconds, but it shot many feet up in the air. If you want to play more with this experiment, you could also compare how different sodas react: https://www.youtube.com/watch?v=iS2vG1o7Op4
Pop a cork: As always, we had more experiments than we had time for. You could use a test tube with a stopper or a glass bottle with a tight-fitting cork. Fill with either citric acid, baking soda, water or vinegar/baking soda. Test to see what quantity you need to pop the cork. http://childcentralstation.com/2011/08/perfecting-blowing-the-cork.html.
We also considered melting Styrofoam with acetone, and playing with the polymer. But given concerns about acetone toxicity, we decided not to do this. But, in case you’re considering it, I have to tell you that when I tested it, it didn’t work as I expected. When I was a kid, you could take regular nail polish remover, dip a Styrofoam cup in it and it would dissolve away. I bought nail polish remover from the drug store, being sure to get the acetone sort, and it didn’t work – it did have other chemicals mixed in, so maybe modern remover is just not a high enough concentration acetone – others recommended that I get acetone from a chemical supply company instead if I wanted to do this experiment.
Snack and Circle Time
After our experiments, we came inside for snack. While they ate, I read the book 11 Experiments That Failed by Offill and Carpenter. This is fun and silly and would be my recommended book to read on a week when you discuss the scientific method. Here is a sample experiment: “Experiments with Perfume. Question: Will seedlings grow if given Eau La La instead of water? Hypothesis: Seedlings will like Eau La La better than water. What you need: pots, dirt, seedlings, water, fancy perfume. What to Do: Place dirt in pots. Plant seedlings in dirt. Water one pot with water. Water other pot with perfume. Watch. What happened: Mom cried. Seedlings died.”
Fizz. Then we made something that website in Australia and New Zealand call Sherbet but that isn’t what I think of when I think of sherbet. It’s a fizzy powder not an ice cream substitute. With the kids, I called it fizzy candy powder and compared it to Pop Rocks and Zotz. The recipes I found were for citric acid crystals, sugar, baking soda, and drink crystals (koolaid?) to give it a little flavor.
In my grocery store, I found “True Lemon” which is citric acid and lemon oil. We mixed 1/2 teaspoon True Lemon, 2 teaspoons sugar, and 1/4 tsp baking soda.
I reminded the kids of last week’s experiment where we cut open lemons and sprinkled baking soda on them – as soon as the baking soda hit the juice it fizzed. I told them the true lemon was lemon juice that was all dried out, and that it needs water to react. So then we sprinkled a little into a cup of water – it fizzed. Then I had kids open their mouths, I sprinkled just a little on their tongues and they closed their mouths and let it fizz. In the morning class, 80% of the kids tried it and the 5 – 6 year old boys wanted to try it again and again. In the afternoon class, I first offered it to some hesitant kids and they refused, so only about 25% of the kids tried it, and one of the young ones was a little distressed by the experience – we had to encourage him to rinse the taste quickly by drinking water and eating more snack.
Because young children thrive on routine, we try to have the same structure to our class every week, where they explore all our activities hands-on for 20-30 minutes, then we do an opening circle where we explain the science behind what they’ve been experiencing, then they do them all hands-on for another 30-40 minutes then outdoor time and closing circle. But this week, we had several activities that a) would require very close supervision, b) could only be done once or twice so we wanted everyone to see it, and c) could make a really big mess. So, we needed to do things differently, with 20 minutes of hands-on projects, 5 minute circle, 60-70 minutes of outdoor demos and hands-on alternating, 10 minutes of circle and snack and a very quick outdoor hike.
If you’re working with just a couple kids, you can ignore this section – but if you’re working with a group, be sure to think about process!!
In the morning session, we were differing from our normal routine and we failed to think through the kid-management process in detail. And even though only 5 kids were there that day, it was pretty chaotic. When I was trying to do a demo, they’d all be swarming up around me. When they were doing hands-on experiments, they weren’t listening well and were trying to jump ahead in ways that would make the experiment fail. And when I was cleaning up one experiment and prepping the other, they were running around in circles. It was crazy!
So, for afternoon class, we made a plan and had a whole different approach. And with 11 kids, it was MUCH calmer than our 5 kid morning!
Prep: I’d done most of this for morning, but refined it more for afternoon. Here’s what I ended with… For each experiment, I had all the materials I would need for it in its own designated plastic tub, out of the kids’ sight. Each tub had its own measuring spoons and cups and everything so NOTHING needed to be moved between tubs. I did things like open and break up all the alka-seltzers in advance so I didn’t have to do it while kids waited. I had a classroom volunteer who I’d told ahead of time that when I finished each experiment, I would hand him a tub and he’d carry it away and handle all the clean-up while I went on to the next one. My co-teacher was my designated assistant during experiments, and during transitions between experiments, she would lead the kids in a sitting-in-your-chairs Simon Says game, which helped to keep them focused on listening!
Opening Circle. In the morning group, I was in a hurry and tried to do opening circle at an activity table and without doing a gathering song, and I just couldn’t get their attention focused on anything I was saying! In the afternoon, we gathered in our regular circle area. We did a call and response song, and it made all the difference in getting all the kids’ attention focused on the same thing!
During opening circle, I explained that outside we would be doing some demos and some hands-on, but that some were messy and some were dangerous, and all would only work if they could do a good job of listening and paying attention. I had each carry a chair outside, and put all the chairs in a line and each sat down. Then we took some PVC pipe and made a safety line halfway between them and my work area, telling them not to cross that without permission.
I would do a demo while all were sitting, then call up a group of four or five kids up to the line to do the experiment while the others sat in their chairs and watched. My 5 – 7 year olds came up to the line on their own. For the 3 and 4 year olds, I asked the parents to help them one-on-one.
For film canister rockets, we assembly lined: I would go down the line, hand each kid a canister and a lid. My co-teacher would go by with the pitcher of water and fill each halfway. Then we’d work together. While the child held the canister, I’d drop in the tablet, cap it, and hand it to my co-teacher. She’d flip and set down. She’d be careful not to shake the first couple, then shake a little and the last one got a bigger shake, so they’d all blow at about the same time. Then we’d have to find all the film canisters, which can travel quite a way! Then we’d bring up the next line. Every child got to do the experiment twice.
For Ziploc time bombs, we had four kids on the line, and I took one up to make a baking soda packet then sent them back behind the line, then the next made a baking soda packet, and so on. Then I called up child A and gave them a bag to hold. I added the water, my co-teacher added the vinegar. The child went back to the line, holding the bag. Once everyone had a bag, I went down the line, doing a quick: drop the baking soda bundle into the bag. Seal tightly. Toss to the ground behind me. And then watch them all explode! Every child did the experiment once.
All in all, it was a fun ending to our chemistry unit!
I wish I had more pictures, but our hands were busy! Many of the posts I link to above have photos and videos of the experiments in progress.