Fizzy colors

Looking for a good experiment for Jr. scientist E, at my wife's suggestion I went back to an old fizzy standard - mixing baking soda and vinegar. To make it more interesting, I put down a drop of red food coloring and a drop of blue food coloring, with the baking soda and vinegar in the middle. As the fizzy mess spread, it took up the food coloring. Jr. scientist E just stared intently at the bubbly concoction (I think with interest!), getting transfixed each time I added more baking soda or vinegar to restart the fizzing.

Ice melting experiment

We had previously used salt to briefly drop the melting point of ice. This time we tried it on a larger scale. We made two ice cubes. The first one (red in the video) was made using water that had Epsom salt dissolved in it. The second one (green in the video) was made using plain water. This wasn't exactly the cleanest experiment - the plain water cube ended up noticeably bigger and was frozen for a shorter period since we already had salt ice cubes sitting around - part of a long-term experiment I'll write about when it's finished. But I expected the effect to be large enough that the general results would be unaffected. As shown in the video, the salt ice cube did melt much faster (about half an hour compared to 1.5 hours for the albeit larger plain water ice cube). You can see from the pool around the edge of the plate how much quicker the salt ice cube was melting. The two ice cubes also melted in very different ways. The plain water cube primarily just got smaller. It still had the typical smooth edges of an ice cube. The salt ice cube started looking very rough and "eaten away" even though it started out smooth. The one oddity was that the plain water ice cube started melting much quicker. We may need to do a more controlled experiment. Although Jr. scientist A enjoyed watching the ice cubes melt, I was surprised that he showed little interest in the sped up video, which I thought would be easier for him to grasp.

Good clean fun

Today we did an experiment that Jr. scientist A named the messy messy experiment. We made some bubble mix (water + dish detergent)and headed outside to play with bubbles. We used a funnel to make different sized bubbles (depending which end we blew into) and tried out a new bubble maker -two straws connected with string- with mixed results. The experiment ended with playing around in puddles of bubble mix and lots of fun.

Hand-crank flashlight

After getting a hand-crank flashlight at the store, we decided to try to build our own mini version. We used a small electric motor and a couple LEDs. When we manually spun the motor (using it like a little power generator), the LED lit up, much to jr. scientist A's delight. Even cooler, when we had the two LED lights connected with opposite polarity (switching where the positive lead went), one would light up when we spun the motor in one direction and the other would light up when we spun the motor in the opposite direction. Very cool experiment.

Growing corn, a summary

Our corn growing experiment is finally at an end. We went from popcorn kernel to ears of corn. I have to admit I didn't imagine that we would actually pull this off. We knew almost nothing when we started - even mistaking the flowering part of the corn stalk for the corn - but with a lot of luck (and some research along the way), we actually grew corn. Jr. scientist A loved watching his corn grow and get taller than him. He was so excited when we got to pick the first ear of corn - he wanted to tell everyone! Now what can we try to grow next year?

Mentos-powered fountain

I've been wanting to do this one for awhile. We added mentos to diet coke and got a big fountain of cola. We tried to add 4 mentos but couldn't get more than 3 in before the fountain started (I had also hoped to get far away before it went off, but oh well). Jr. scientist A really liked this one. Jr. scientist E also joined us for her first experiment, but I think it was too fast (a few seconds in total) for her to notice.

Our experiment bears fruit (well, vegetables)

I didn't think it would work, but our corn experiment is actually starting to grow corn, and the tiny corn is getting bigger each day. The plants are now taller than jr. scientist A and are still growing. Who would have thought our humble little popcorn kernels would grow into this!

Making colored paper

We're trying to see how the sun affects different colored paper, so we decided to make our own colored paper with printer paper and food coloring. We cut strips of white paper and filled some shallow pans with water and food coloring. We let the strips soak in the pans overnight and moved them to wax paper the next morning to dry (flipping occasionally). Once they dried, we had pastel-colored paper!

Catapult

We built a mini catapult using popsicle sticks, rubber bands, and a bottle cap using instructions from Supercharged Science It was quick to make and worked really well. Jr. scientist A had fun learning how to work it (and where NOT to stand when you're using it) and catapulting leafs, berries, and crumbs.

Vinegar and baking soda balloon, take 2

We decided to revisit an old favorite experiment - inflating a balloon using vinegar and baking soda. Since last time we had trouble getting the balloon on the bottle before all the gas escaped, we tried poking a hole in the bottle cap and attaching the balloon to the bottle cap. That let us quickly screw the cap on, balloon attached, before the gas escaped. We even tried filling the balloon with vinegar so that we could squeeze it out of the balloon and into the baking soda filled bottle after the cap was on. That let us control the reaction and capture the gas pretty well.

From seedling to plant

We planted our seedlings that we grew from popcorn kernels. We had a fun time filling biodegradable pots with soil, sticking in the seedlings, and planting the pots. I wasn't really sure if they'd survive the transplant, but we dutifully watered them every day. Within a few days we started seeing little plants poking out of the soil. Since then they've just kept growing and growing. It's neat to see what our little popcorn kernels are turning into. We're now working on trying our hand at baby carrots.

From seed to seedling

After a few fun trips to our local plant nursery, I thought it would be neat to show jr. scientist A. how a seed turns into a plant. We took a plastic container and lined the inside wall with a damp paper towel. Then we stuck a few popcorn kernels between the paper towel and the wall of the container. With dutiful watering to make sure the towel stayed damp and a nice sunny windowsill, we started to see some sprouting in a few days. A few days after that there were little purple roots climbing downwards and little greet shoots climbing upwards - how do they know how to do that! Tomorrow we're planning on transplanting our seedlings to a dirt pot to let them grow bigger.

Raising a butterfly

Our local kids museum has an annual adopt-a-caterpillar event. You get a very tiny caterpillar to take home in a small container. Over the course of a couple weeks you get to see it get bigger and bigger. Then, as jr. scientist A liked to recite, it would "build a cocoon, stay inside for two weeks, push its way out and be a beautiful butterfly!" (the last two words were always said loudly with arms up in the air). It was a really neat experience, although jr. scientist A was sad when we released our little friend into the wild.

Make-shift bubble blower

I promised jr. scientist A that we would make bubbles, but I couldn't find any of our bubble blowers. We decided to try to make some with objects we had around the house. One of the best bubble makers was an empty toilet paper roll. We dipped it in some bubble mix and then blew into the other end. If we blew slowly we got really big bubbles (although they often popped while still attached). It was a lot of fun, and when the toilet paper roll got soggy, we just let it sit for a couple hours and it was ready to be used again.

Meeting in the middle

Time for more fun with food coloring. We had previously used two colors to see whether salt water was slower to diffuse than fresh water. This time we repeated the experiment with two containers of differently colored fresh water. To our surprise, although the colors eventually seemed to meet in the middle, the red took days longer than the yellow color. It seems that whatever makes the different colors causes them to diffuse at different rates. We'll have to play around with that some more.

Crystal growing mediums

Since our previous attempts at growing stalactites have yet to yield anything remotely resembling a stalactite, we decided to take a step back and do some pilot experiments. There seems to be a few problems that potentially need to be addressed. 1) How do you get a nice slow drip for the salt water so that the crystals can grow over time? 2) What type of materials will the stalactites grow best on? 3) How do you refill your salt water solution without dissolving the already formed (water soluble) crystals (i.e., whatever makes the slow drip has to either never release the solution faster than a drip or be detachable)? I'm sure there's a few more we'll run into.

We've previously made some good progress on the first problem. We decided to attack the second problem by trying to grow crystals on different materials. We made our crystal solution, dissolving as much salt as possible in super heated water. This time we used table salt - nice and safe to handle and eat (good for a toddler hands-on experiment, that is, once the water has cooled). We poured the crystal solution over cardboard, paper, wood (a popsicle stick), and wool yarn. We set the materials in a window for a couple days and then checked on our results. The crystals grew everywhere (including on the plastic container the materials were in), but they just looked like big grains of salt on most of the materials. The one that stood out was the yarn (shown above, enlarged). There it seemed to form large crystal structures that looked like they'd be ideal for the beginnings of stalactites. I think we found our crystal growing medium!

Invisible paintings

We made some invisible paintings, dipping paintbrushes into lemon juice. We tried to get them to appear by heating them in the sun, but that wasn't warm enough. Instead, we found out that putting them in the oven at 350 degrees for about 5 minutes made them show up quite well. Jr. scientist A was quite proud of his now-visible paintings and decided to put them up on the fridge (o.k., the picture above was mine, which Jr. scientist A didn't deem good enough to put on the fridge!).

Unconventional bubble maker

Once again we used pressure created by warming air. We took a frozen empty bottle (my new motto is always keep an empty bottle in the freezer) and dipped the opening in bubble mix to form a soapy film over the opening. We put the bottle down and slowly a bubble started growing out of bottle. Squeezing the bottle, we could make the bubble grow quicker - o.k., it's just from the warmth from my hands, but it looks like I'm squeezing the bubble out of the bottle. Jr. scientist A had great fun popping each bubble as it formed.

Dancing pill bottle

Following up on our rubber band-powered boat, we made a dancing pill bottle. We drilled a hole in the top of a pill bottle. Then we put a rubber band around a popsicle stick and stuck the rest of the rubber band through the hole in the cap. We wrapped the other end of the rubber band around the bottom of the bottle and put the cap on the bottle. Finally, we spun the popsicle stick around to wind up the rubber band. I was hoping we might get a little helicopter-like lift out of it, but instead, it made the bottle dance around - still pretty neat.

Paper helicopter

We did a science experiment I found in the book "The Usborne Book of Science Fun." We made an easy-to-build paper helicopter (takes less than 5 minutes to make). We also made a more durable version out of art foam. Because of the way the wings stick out, the helicopter spins around as it makes its way to the ground - just let it go from a height and it does the rest. We even tried dropping it over a third floor balcony for an extra long spinning flight. A fun little experiment.

Diving pen cap

We made a pen cap that dives on command. We took a pen cap, attached a string loop around it and added four paper clips to the loop as weights. We then filled a big soda bottle with water until it was almost completely full. We dropped the pen cap into the bottle and screwed the top on tight. When we squeezed the middle of the bottle, the pen cap sank because the air bubble inside it was compressed. When we let go, the air bubble expanded again and the cap floated back to the top. It took a little practice to get the weighting and water level right. When the cap capsized, causing the air bubble to escape and the cap to sink to the bottom, we used a magnet to drag the paper clips and cap to the top so we could reach in and pull it out without emptying the bottle.

Scaredy-cat toothpicks

More fun with surface tension (one of Jr scientist A's new favorite phrases). We did an experiment showing that floating toothpicks will run in terror from soap. We arranged the toothpicks in a bowl of water so that they formed a complete enclosure - this helps them keep their relative position. You need to make sure that every toothpick, including the last one, is above another toothpick on one end and below another toothpick on the other. Then we covered the end of a new toothpick in dish detergent and gently put the soapy end into the water in the middle of the other toothpicks. Instantly the floating toothpicks moved away from the center, scattering to the edges of the bowl. A fun experiment that has a big "wow" effect, is easy to re-set up (just wash the toothpicks and bowl and refill with new water), and with a little guidance, can be a hands-on experiment for a little tyke. Now Jr. scientist A keeps asking me to do that experiment again!

Rain shadows

Even though it wasn't raining, we decided to make rain shadows. We used a spray bottle full of water as the rain. We put different objects on the dry cement and sprayed all around their edges. When we removed the objects we had a "shadow" of the object that had been there. We even made a rain shadow of Jr. scientist A. A fun experiment.

Stopping color in its tracks

This experiment was hard to pull off, but very cool once we got it to work. Since salt water is denser than fresh water, you should be able to get fresh water to sit on top of salt water, rather than all mixing together. The idea is that you put clear salt water in one container and fresh water with food coloring in another container. When you poor the colored water into the container with the salt water, the colored water should sit on top of the salt water, giving the appearance that you've stopped the color in its tracks. The only problem is that the force of pouring the colored water makes it go to the bottom of the second container before rising to the top, coloring the salt water in the process. Remembering how we got a paper clip to float using surface tension, we floated a piece of cardboard on top of the salt water and carefully poured the colored water onto the cardboard. The trick worked - although we had one attempt where some of the colored water missed the cardboard, greatly diminishing the wow factor. But when it worked, it was surreal.

Turning salt into glue

We tried to pick up ice cubes with string, using salt as the "glue." The idea is that, when you put salt on ice with the string resting on the ice, the salt lowers the ice's melting point, causing it to start to melt a little. As it refreezes, the ice freezes around the string. Our first attempt was a dud. You could feel that the string stick a little to the ice, but pulled right off. But it turned into an accidental experiment on states of matter - jr. scientist A was delighted to find that when he held the ice in his hand, it turned into water. For our second attempt, we realized that we needed to first wet the string. That turned out to be the key. With our salt and wet string, we were able to lift up the ice - although the effect was somewhat short-lived.

Rubber band-powered boat

We used a rubber band-powered boat to investigate potential and kinetic energy. The boat used popsicle sticks held together with hot glue for the body and tape-covered cardboard for the paddle. A rubber band attached to the boat body goes around the paddle. The boat is supposed to go by turning the paddle, storing energy in the rubber band, which is released when you let go of the paddle. Its maiden voyage went well, paddling slowly in the bathtub. Unfortunately, before we could try a stronger rubber band that might store more energy, the boat fell apart. I guess hot glue is not as waterproof as I thought. We'll have to try to make some other rubber band-powered toys.

Stomp rocket

Finally, a pressure-based rocket experiment that works! Jr. scientist A got a stomp rocket for his birthday. The kit has a Styrofoam rocket that gets launched by stomping on an air-filled container, sending air out a tube, creating enough pressure to launch the rocket sitting on the tube. We got the rocket to go high, we got the rocket to go far - a good time was had by all. We also played with the launcher itself, pushing on the air-filled container and having Jr. scientist A feel the air that came whooshing out so he could see how it all worked. Hmm, I wonder what else we can launch...

Water race

To try to show that, even though water looks the same after you dissolve salt in it, it's changed, we decided to compare the speed of diffusion for salt water and fresh water. We filled one bottle with fresh water, dyed green, and a second bottle with water with Epsom salt dissolved into it, dyed red. Then we rolled up a paper towel and put an end in each bottle. The green fresh water started climbing the paper towel. At first it looked like the red salt water was just sitting there, but we checked and the un-dyed paper towel coming from the red was wet, while the paper towel from the fresh water was only wet where it was green. Eventually the red color started moving along the towel. It looks like the salt slowed the diffusion of the color, but not the diffusion of all the water.

Making water run upstream

We decided to try to make water run upstream, so to speak, using diffusion. We filled a bottle with colored water. Then we took a long piece of paper towel, rolled it up, and used string to keep it rolled up. We put one end of the paper towel in the water-filled bottle and the other end in an empty bottle that we put on a raised platform. Nearly instantly the colored water started creeping up the paper towel. We quickly learned that a paper towel saturated with water is much heavier than a dry paper towel and we had to add supports to hold the paper towel up. Throughout the evening we watched its slow progress. We checked on it in the morning and, to our surprise, the water hadn't made it all the way to the other bottle. Instead, it stopped part-way up, leaving a dark ring of color, followed by dry paper towel. I guess diffusion will only go so far.

Mixing colors

Jr. scientist A got a science kit for his birthday that included pipettes and tablets to make colored water, so we started mixing colors together. It took some practice for him to get used to using the pipettes, but once he got it working, he was intrigued that mixing two liquids together created something that didn't look like either of the things he started with.

Vacuum in a bottle

As part of our next attempt to make stalagmites and stalactites, we tried to get our salt-water solution to slowly drip out of a container. We poked a hole in the bottom of a plastic bottle. By screwing on the top of the container, we could slow the flow of the leak - as water leaked out, there was no opening for air to go in, causing the pressure to decrease inside the bottle, creating a vacuum. Jr. scientist A loved seeing the liquid go faster or slower out the hole in the bottom as we unscrewed the cap and screwed it back on. A big hit!

Baking soda and vinegar balloon

Having previously mixed baking soda and vinegar together to make a bubbly mess, we decided to try to harness that released carbon dioxide to inflate a balloon. We poured baking soda into a bottle, added vinegar, and then quickly put a balloon over the opening of the bottle. Very quickly the balloon started to inflate, much to Jr. scientist A's delight. A fun and repeatable experiment - just a little hard to get the balloon on in time.

Stalagmites and stalactites, take 2

Our second attempt at making stalagmites and stalactites with salt crystals. This time we used a paper towel to connect the two jars filled with Epsom salt dissolved in water. The liquid did slowly travel up and across the paper towel, making the paper towel rigid, and we got some crystals forming below the paper towel, but nothing that looked like stalagmites or stalactites. We'll have to keep trying.

Cold air balloon

We tried to inflate a balloon using cold air by sticking a balloon over the opening of an empty bottle we took out of the freezer. The idea was that as the air warms up, it expands, inflating the balloon. We left the bottle and balloon out overnight to warm up the captured air and found a somewhat inflated balloon in the morning. Not a very impressive effect. Maybe we need a bigger bottle.

Floating paperclips

Our previous attempt to use surface tension to float objects found that a paperclip was too heavy. Looking around online, it seems like there might have been a flaw in our approach. By dropping the paperclip in, we might have broken the surface tension. This time, we first floated a piece of paper and dropped a dry paperclip on the paper. Then, using a pipe-cleaner, we pushed the paper under water, being careful to not touch the paperclip. The paperclip stayed floating on top of the water. I then gave Jr. scientist A a couple paperclips to drop in the water and he watched in amazement as his paperclips just dropped to the bottom while mine floated (thanks to the paper trick I used with mine). True to the physics of floating-by-surface-tension, we added a squirt of dish detergent to the water and the floating paperclip sunk like a stone... er... like a paperclip.