Tag Archives: Physics

Electric play dough – Fun with squishy circuits

Squishy circuits

Squishy circuits combine two of my kids’ favourite hands-on activities: play dough and electric circuits.

You can either just use conductive play dough in your circuits. Or, to extend the learning, you could mix up a batch of insulating play dough that doesn’t conduct electricity.

What you need

Squishy circuits

Conductive play dough ingredients

* Flour – 1 cup

* Salt – 1/4 cup

* Vegetable oil – 1 tbsp

* Water – 1 cup

* Cream of tartar (3 tbsp) or lemon juice (9 tbsp)

* Food colouring (optional)

Mix all the ingredients together in a pan on the stove over a medium heat, then knead to form a dough.

For more detailed instructions and other useful tips, head over to StiMotherhood.

Squishy circuitsInsulating play dough ingredients

* Flour – 1 cup

* Vegetable oil – 3 tbsp

* Sugar – 1/2 cup

* Food colouring (optional)

* De-ionised or distilled water – 1/2 cup

Mix all the insulating play dough ingredients together in a bowl, then knead. Warning – this batch will be stickier than the conductive play dough.

Apparently de-ionised water  is used to prevent limescale in cars and irons. (Confession: I ordered it from Amazon and then got impatient and bought some at my local car supplies shop. Any suggestions about what to do with 5 litres of de-ionised water? ‘Do more ironing’ is not the kind of thing I mean.)

To play with the dough, you will also need a 9V battery and a battery holder with connecting wires, and some LED lights.

Before you play with your electric play dough

Before they play, show your kids what to expect and get them excited with this squishy circuits video.


The science of squishy circuits

Squishy circuits provide a perfect demonstration of how electricity takes the path of least resistance.

If an electric current has to travel through an LED bulb to complete a circuit, it will do so and light up the bulb.

But if the electricity can find an easier path (like through a piece of conductive dough), the bulb will remain unlit.

Squishy circuits
Circuit made of conductive playdough and LED bulbs

How to use the insulating play dough

Use insulating dough to bridge gaps between pieces of conductive dough.

Electricity can’t travel through the insulating dough. Instead, it has to travel through – and light up – the LED bulbs.

squishy circuits
Squishy circuits creations
Squishy circuits
Left: Circuit made from conductive play dough (bulb unlit). Right: Circuit with both conductive and insulating play dough (bulb lights up because electricity can’t pass through the orange insulating dough so passes through the bulb instead)

Squishy circuits

Benefit from my mistakes

I have a habit of seeing a cool activity online then gathering supplies and diving in without referring back to the original instructions. Which is why we first tried to power our squishy circuits with a couple of AA batteries.

Underpowered circuits are a bit of a dampener on kids’ enthusiasm.

Luckily J(9) and C(11) were happy to switch to regular play dough and reconvene with the conductive sort on another day, once I’d bought some 9V batteries.

Squishy circuits creationsAA batteries are probably fine if you have enough of them (and sufficient battery holders), but I’d recommend using 9V if you can.

Finally – do wipe down your metal wires after they’ve been in contact with the conductive play dough, so they don’t rust.

I first came across the idea of squishy circuits at StIMotherhood. Do head over there for tips on how to get the most out of squishy circuits play.

And see  this great TED talk all about squishy circuits by the lady who invented them.



More fun hands-on science

The amazing water trick – Investigating density

Alien soup – How to separate mixtures

Fun science – What dissolves?

Hands-on hydraulics

Chemistry for kids – How to separate water into oxygen and hydrogen using electrolysis

The science of how candles burn

The science of flying

How to make a balloon hovercraft

Gummy bear science – Osmosis in action

Fun with magnets

Midsummer potions

Edible science with ice and salt

Air pressure experiments

Elephant’s toothpaste – Fun with catalysts

Creative science with ice, salt and colour

Clay model of the Earth’s layers

How to simulate the rock cycle with crayons

How to make butter – Fun with emulsions

Fun with acids and bases – How to use red cabbage as an indicator

Fun with polymers – How to make slime and plastic

2 Fizzy fountains

Copper-plating a nail

Hands-on science – Is light a wave or a particle?


Squishy circuits

A note to my kind friends who are wondering what became of my next post about our Spanish adventure: This week someone with a huge Facebook following (I wish I knew who) shared my elephant’s toothpaste post, resulting in 70,000 extra visitors here.

Once I’d picked myself off the floor, I was inspired to get around to finishing this post on squishy circuits.

More about Spain soon. 🙂

* * *

I’m appreciatively linking up here:

The Weekly Wrap-Up – Weird Unsocialized Homeschoolers

Science Sunday – All Things Beautiful


Hands-on science: Is light a wave or a particle?


Scientists argued for two hundred years about whether light was a shower of tiny particles or a series of waves. Then just as the debate was settled, Einstein came along with an answer that would have set Newton’s head spinning.

We decided to explore the properties of waves and light for ourselves.

Hands-on science: Is light a wave or a particle
Simple wave tank with plasticine obstacles

What happens when waves meet an obstacle?

Hands-on science: Is light a wave or a particle

When waves meet an obstacle, they curve around it.

If light curved around an obstacle, we would expect the obstacle to cast a fuzzy shadow. But anyone who’s played shadow puppets knows that shadows can have fairly sharp edges.

Hands-on science: Is light a wave or a particle
When light meets obstacles, sharp shadow are created

Because of this, sixteenth century scientist Isaac Newton believed that light must be made of millions of tiny particles moving in straight paths.


What happens when waves pass through a small opening?

Hands-on science: Is light a wave or a particle

The waves spread out as they pass through, as if the opening was the source of the waves.

Seventeenth century scientist Christian Huygens pointed out that light also spreads out through an opening. If you were to put a lamp behind a wall with a small hole in it, light coming through the hole wouldn’t stay in the shape of the hole – it would spread out.

Huygens said that because light diffracts, it must be made of waves. He pointed out two other properties of light that supported his theory.


Hands-on science: Is light a wave or a particle
Light appears to bend

A pencil placed in a glass of water appears to bend at the water’s surface. This is because light travels more slowly through water than it does through air.

Huygens said that if light waves travel at different speeds through different materials, the change in speed would cause the waves to bend.  We call this apparent bending refraction.

We performed a cool trick to demonstrate refraction. {1 minute video below} I should have made it clear in the video that the camera stayed still throughout the demonstration!



When two sets of waves cross each other, they interact in an interesting way. In some places they cancel each other out, while in other places they add to each other and create a stronger wave. This phenomenon is called interference.

We created two sets of waves in our wave tank. (We would have observed a larger interference pattern in a bigger tank.)

Hands-on science: Is light a wave or a particle

In 1801 Thomas Young proved that light also produces interference patterns.

You can observe light interference patterns by looking at a source of light between two pencils.

Hands-on science: Is light a wave or a particle
Observing light interference patterns

When the pencils are almost touching, you can see a vertical pattern of light and dark lines. The dark lines are where the light waves are cancelling each other out.

Thomas Young was the first person to calculate the size of light waves. His measurements explained why light diffraction is so difficult to see – light waves are so small that that can only bend around the tiniest of obstacles.

Light as both wave and particle?

By the 1800’s scientists were sure that light was made of waves. But in 1900 the particle theory reappeared!

Albert Einstein and Max Planck showed that light sometimes behaves like a wave, but sometimes acts like a particle. Their discoveries led to the branch of science known as quantum physics.


We’ve been reading aloud Waves: Principles of Light, Electricity and Magnetism, a wonderful living book I highly recommend. We got most of our experiments from this book.


We read about Einstein and Planck’s fascinating discoveries last term in the Uncle Albert books.

Hands-on Science: Is light a wave or a particle

Veritasium has a great demonstration of wave interference, and recreates the original double slit experiment which ‘proved’ (for a while!) that light was a wave:




I’m appreciatively linking up here:

Science Sunday at All Things Beautiful

Weekly Wrap-Up at Weird Unsocialized Homeschoolers

Unschooling Plans – Science and History

Unschooling science and history

Here’s what we have planned for science and history this term. My children intend to keep me very busy!

See this post for our unschooling plans for maths and English.



C(10) wants to “explore the laws of physics. Like, what makes vacuum cleaners work? How do aeroplanes and helicopters fly? What charges up batteries?”

I’ll be learning this alongside the kids here. I enjoyed physics it at school but didn’t study it for long. When I was 13 I missed a term of school because of a road accident and had to drop a subject (physics). The time has come to catch up on what I missed!

J(8) threw in, “And I want to learn about quantum physics.”

“Sure!” I replied brightly, wondering where on Earth I’d find resources to teach quantum physics to an 8-year-old (or a 43-year-old).

I needn’t have worried – the scientists have it covered. Just look at this Minecraft Mod, designed to teach kids about quantum physics. And YouTube has dozens of videos on the subject. (The kids may be teaching me some science this term.)


J(8), meanwhile, wants to “make more potions,” so we’ll do more activities like Midsummer Potions, Alien Soup and Fizzy Fountains.

unschooling science
“Potions class”

Science investigations that all students should do before high school

In our spare moments I’ll use Phyllis’s wonderful collections of science investigations that all students should do before high school and concoctions for play. We’ve done many of these already but I’m eagerly following Phyllis’s blog so we don’t miss any fun.

unschooling science and history
Diet coke geyser fun

History (with a bit of English and science overlap)

C(10) and I will continue with our chronological study of world history (we’re two-thirds through The Story of the World volume 2). We’re especially looking forward to learning about the Elizabethan period and Shakespeare.


Shakespeare’s Globe in London is showing Much Ado About Nothing in April so we’re going to study the play and then see it performed. This week we laughed out loud at the Andrew Matthews and Tony Ross retelling.  Next we’re going to read the No Fear Shakespeare (Sparknotes) version, and watch the Kenneth Brannagh movie. And finally – the live performance!

Unschooling science and history

Explorers and navigation

We’ll visit the Royal Museums Greenwich to complement our SOTW study of the early explorers. The children are looking forward to standing astride the Prime Meridian, with one foot in the Earth’s Western Hemisphere and one in the Eastern Hemisphere.

World Wars

J(8) received an illustrated book on the World Wars for Christmas, which prompted him to ask to learn about the World Wars.

He’s more interested in machines and methods of warfare than people and motives so he loves these First World War Fact Cards I recently strewed.

unschooling science and history

There’s plenty of good quality historical fiction about World War I and II. Right now we’re enjoying The Silver Sword in the car, and Puddles in the Lane is our family read-aloud.

I’d like to use videos, too – does anyone know of any good videos about the world wars that are suitable for children?

Our local kids’ history club is running a workshop on the First World War this afternoon, which will get us off to a great start.

Do you have any suggestions for resources we might like? I’d love to hear from you!

Next time, in the last post in this unschooling plans series, I’ll share my children’s project plans for this term.


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Entertaining and Educational

Weekly Wrap-Up

Collage Friday

Hands-On Hydraulics – Science Fun for Kids

hands-on hydraulic

This hands-on hydraulics experiment is a fun way to investigate the power of liquids.

We used hydraulic power to create a simple machine which our Lego mini figs – and all the family – had fun playing with.

Our hydraulic theme-park even inspired a movie!

A liquid under pressure can apply a lot of force and this can be used by machinery to do work. Using liquids like this is a branch of engineering called hydraulics.

Science Experiments for Kids

Hydraulic Lifter Experiment

What You Need

  • short length of tubing
  • balloon
  • empty can
  • tape
  • empty plastic bottle
  • funnel
  • heavy book
  • water
  • scissors

hands-on hydraulic

What you do

{I’ve added a steps 1 and 2 to the instructions given in Science Experiments for Kids, to give you the benefit of our mistakes.}

1. Stretch the balloon by blowing it up and letting the air out again.

2. Attach the tubing to the empty balloon and seal the join with tape. Check the join is water-tight by attaching the funnel to the other end of the tube and filling with water. Remove the funnel and drain out the water.

3. Cut the empty bottle so that it is just a little taller than the can. (We should have cut a bit more off ours.) Use a pencil to make a small hole near the bottom of the bottle.

4. Feed the free end of the pipe through the hole in the bottle, leaving the balloon inside.

5. Put the heavy book on top of the bottle.

6. Attach the funnel to the pipe and fill with water. (Hold the funnel up high to quickly release any air bubbles.)

hands-on hydraulic

What happens

The water-filled balloon lifts the can, which in turn lifts the book.

hands-on hydraulic

The balloon feels very firm.

hands-on hydraulic

The scientific explanation

The weight of the water in the funnel creates enough pressure to force water into the balloon. This force is in turn transmitted through the balloon to lift the book.

Fluids transmit forces more effectively than gases because they can’t be compressed, even under pressure.

Hands-on hydraulics fun

We wanted to apply what we’d learned to create something like this very cool hydraulic elevator.


Unfortunately we couldn’t get our syringes and pipes sealed tightly enough to make it work.

Instead, C(9) had the idea of using hydraulic pressure to create a fun ride for Lego mini figures.

hands-on hydraulics
First of all C(9) made a hydraulic see-saw …
hands-on Hydraulics
… which turned into a “Blue Sky Bouncer” theme park ride which had the mini figs queuing up for turns
hands-on Hydraulics
C(9) even made a movie trailer promoting her ride using iMovie on her iPad

Real life hydraulics

Liquids are used in many kinds of machines to carry force through pipes.

Most of us rely on hydraulic machines every day, for example when we apply the brakes in our cars or fill them with petrol, and even when we run the dishwasher.

Hydraulics is used to design piping systems, pumps, propellers, water turbines, hydraulic presses, and flow-measuring devices.

Britannica Online for Kids

We enjoyed dipping our toes into hydraulic principles.

There are lots more hydraulics experiments I hope we’ll do in the future. They’re a great hands-on way to learn about the laws of physics, such as Pascal’s Principle.

For more pressure science, see our air pressure experiments.


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Entertaining and Educational

The Homeschool Mother’s Journal

Hip Homeschool Hop



How to Make a Balloon Hovercraft

hovercraft experiment

We’ve wanted to try a hovercraft experiment since we saw a really cool leaf blower hovercraft (like this one) at a science show last year. As we don’t have access to a leaf blower, we used balloon-power!

There are many variations on this experiment. We tried quite a few.  I’ll start with the one that worked best and then show you some of the others. (Maybe you’ll have better luck with them.)

What you need

* old CD

* hot glue gun

* sports cap from a water bottle (the kind that you pull up to drink and push down to close)

* push pin (drawing pin)

* large balloon

* a big smooth surface

What you do

1. Use the push pin to make two holes in the cap near the centre.

Hovercraft experiment

2. Spread a thin layer of hot glue around the base of the bottle cap and attach it to the CD, over the hole. Give the cap a slight twist as you stick it to ensure an airtight seal.

3. Make sure the cap is down (closed).

4. Blow up your balloon and pinch its neck while you attach it to the top part of the cap. (Easiest with two people.)

5. Place your hovercraft on a smooth flat surface. Give it a push and see what happens {not much}.

6. Now, without removing the balloon, pull up and open the cap. Quickly give the hovercraft a push and watch it continue moving. Push your hovercraft back and forth across a flat surface to keep it moving until the balloon is fully deflated.

Notes: (1) I’ve since seen the experiment set up this way in Science Experiments, but without the pushpin holes

(2) I’ve also seen a version that uses sticky tack (Blue Tack) instead of hot glue

Hovercraft experiment
Playing with our hovercraft

The scientific explanation

When you push the hovercraft when the cap is closed (stage 5 above) , friction between the CD and the surface soon stops it moving.

But when you open the cap, air escaping from the balloon cushions the hovercraft. The hovercraft continues moving much farther.

Variations that didn’t work for us {but it’s good to experiment}

1. First we tried making Science Bob’s hovercraft. This involved taping over the CD hole and making six push pin holes in it. No holes were in the lid.

Verdict: A complete dud! I’m not sure what we did wrong, but this hovercraft didn’t do much for us.

hovercraft experiment
Science Bob’s hovercraft

2. The version that eventually worked for us was from Steve Spangler Science. But Steve Spangler suggests making a cardboard collar for the hovercraft.

Hovercraft experiment
Hovercraft with collar

Verdict: We made a collar and the hovercraft worked fine, but it was very fiddly trying to get everything attached and the cap open. We eventually removed the collar in frustration, and found that the hovercraft worked just as well without it.

3.  We tried making a hovercraft just using  a paper plate and balloon.

hovercraft experiment
Paper plate hovercraft

Verdict: Another dud! Perhaps we didn’t make our centre hole big enough?

hovercraft experiment
We found a few other uses for it though!

Hovercraft History

The first modern hovercraft was designed in the 1950’s by Englishman Sir Christopher Cockerel. It crossed the English Channel between Dover, England and Calais, France in two hours.

Until the year 2000, passengers could travel from England to France by hovercraft in just 35 minutes.  Passenger hovercrafts still operate between Southsea, England, and the Isle of Wight.

hovercraft experiment
Southsea to Ryde passenger hovercraft {by Barry Skeates}

Hovercrafts are a type of seaplane, and they require large amounts of expensive aviation fuel to keep their giant air-cushions inflated. This is one of the reasons large hovercrafts are less commonly used nowadays.

Military Hovercrafts

Because hovercrafts are able to cross any flat terrain, including water, marshland, tarmac and sand, they are still commonly used for military purposes.

The biggest hovercraft in the world – the Zubr – recently made the news when it landed on a Russian beach filled with hundreds of sunbathers. A Russian defence spokesman reportedly commented, “What people were doing at the beach on the territory of a military base is unclear.” Okay, then!


History of the Hovercraft – Squidoo

Giant Hovercraft Retire after 30 Years of Channel Crossings

Coming Up

Next time –  How to make a hydraulic lift


I’m appreciatively linking up here:

Highhill Education – Entertaining and Educational – Sept 19

Homegrown Learners – Collage Friday

Hammock Tracks – Look What We Did!

Weird Unsocialized Homeschoolers – Weekly Wrap Up

Teach Beside Me – Share It Saturday

Adventures In Mommydom – Science Sunday

Learn Play Imagine – The Sunday Showcase

Hip Homeschool Moms – Hip Homeschool Hop 9/24/13

All For the Boys – Let’s Hear it for the Boy

2 Fizzy Fountains

Fizzy fountains

Homeschool science is so much fun.  This week we made two very different fizzy fountains. On Monday we let off a diet coke and mentos geyser, and on Friday we created our own “lava lamp”.

Diet Coke and Mentos Geyser

I bought the supplies for this back in June 2012, when we were doing our rocket project, but the instructions for making a diet coke and mentos rocket were evidently too daunting for me to get around to doing it. So when the children recently asked if we could make a diet coke fountain, I was all ready to go.

What You Need

  • large bottle of soda (coloured, diet soda like Diet Coke is best – so you can see the spray, and the spray doesn’t make too much of a sticky mess)
  • pack of Mentos
  • paper/card or Geyser Tube
  • a large outdoor space

What You Do

The experiment couldn’t be simpler to explain. Dump a whole packet of Mentos into a bottle of soda, then stand well back.

The tricky bit is trying to get all the Mentos in at once. Cordie and Jasper experimented with various techniques using an empty bottle. What seemed to work best was loading the Mentos into a piece of paper which had been rolled into a loose cone, while holding a piece of card at the thin end of the cone to keep the Mentos from falling through. The card can then be slid away when you’re ready to set off the geyser.

How Did It Go?

Our Mentos-loading technique worked perfectly the first time. However, our geyser was only about a foot high. Maybe because the diet coke I’d bought for our rocket experiments was four months past its use-by date?!

coke and mentos geyser - homeschool science at navigatingbyjoy

But …we still had a tube of mentos left, so we tried again, this time with a bottle of caffeine-free diet coke I’d been saving to enjoy with a shot of rum at the weekend (I am so selfless in the cause of science). Unfortunately this time our Mentos-loading technique didn’t work so well.  No quick-fire round of mints exploding the surface tension of the coke – instead, the last 8 were hastily shoved in one by one before I scarpered to a safe distance.

The resulting geyser was double the height of our first attempt, but there was no danger of getting our hair wet, let alone the roof. (I felt a bit wistful as I removed my sou’ wester hat.)  But the kids – who hadn’t known what to expect – were impressed.

How Does It Work?

No-one knows for sure! The most popular theory is that the Mentos break the surface tension of the soda, releasing loads of carbon dioxide bubbles at once. These bubbles push all of the liquid out of the bottle in a fantastic explosion.  Steve Spangler Science has a more detailed explanation and some cool videos.

What Might We Do Differently Next Time?

  • use a Steve Spangler Geyser Tube (£4.45 at Amazon) to load the Mentos
  • try using store-brand diet cola (Tesco does 2 litre bottles for 17p)

We will spray our trees with coke yet!

Oil and Water Fizzy Fountain

We found this in Science Experiments: Loads of Explosively Fun Experiments You Can Do.

What You Need

  • plastic bottle
  • vegetable oil
  • water
  • food colouring
  • two effervescent tablets (containing citric acid and bicarbonate of soda)

fizzy fountains homeschool science fun

What You Dopouring water onto oil - homeschool science

  1. Fill a plastic bottle three quarters full with vegetable oil.
  2. Top up with water. (Observe how the water sinks to the bottom because it is denser than the oil.)
  3. Add a few drops of food colouring. (Wait a moment for the colour to sink through the oil, then appreciate the pretty effects as it mixes with the water.)
  4. Break two effervescent tablets in half and drop them into the bottle.
  5. Loosely screw on the bottle top. (Watch your fizzy fountain start to work.)

How Does it Work?

When the tablets dissolve in the water, they give off carbon dioxide. Bubbles of this gas float up through the bottle. When the bubbles attach themselves to blobs of water, the blobs and the bubbles together are less dense than the oil, so they rise up to the surface. There the bubbles pop, and the blobs of water sink back down through the water again.

What We Might Do Differently Next Time

effervescent oil and water fountain

This was a fun experiment – we would do it again. I might make a few changes though:

  • use a smaller bottle (less oil – cheaper!)
  • use less food colouring. We used red, blue and green which together turned the water dark brown.
  • use indigestion tablets instead of (orange) vitamin C tablets (another reason why the water turned brown?)
  • shine a lamp through the bottle
  • add glitter to the fountain
  • experiment with different kinds of oil e.g. olive oil

Bonus Fun

We hunted out Big J’s lava lamp and enjoyed watching the pretty patterns as warmed wax floated up to the top and then sank again as it cooled.

What Next?

Next week we’re going to investigate polymers, making slime and plastic. Sounds fun!

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