If there is a similarity between scientists and children, it is their interminable curiosity and enthusiasm for learning new things. However, the process of learning is fruitless if it is not followed by its application. Without putting that knowledge to use, our grip on a concept gradually wanes. Practical knowledge is essential and should be practiced from a young age to instill rigor and ingenuity into budding scientists.
With that in mind, here are some awesome and simple experiments for your children to experience their own “Eureka!” moment. These can be performed using mundane household products and also, unlike Archimedes, children can sprinkle in some food coloring to make their experiments even more scintillating!
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1) Potato Power
This is an innovative experiment to depict the working of an electrochemical battery highlighting the conversion of chemical energy into electrical energy. The experiment requires two potatoes, two copper pennies, two zinc or galvanized nails, wires with alligator clips (preferably) and a low-voltage LED.
- Thrust one penny and one nail into opposite ends of the first potato. Thrust the other penny and nail into the second potato in the same way.
- Now, with the help of wires, connect the nail in the first potato to the penny in the second by latching onto them with the alligator clips. In an absence of clips, strip off the insulation and wrap the copper wire around the materials.
- Lastly, connect the open wires from the remaining nail and penny to the LED terminals. The penny must be connected to the LED’s positive terminal and the nail to the negative terminal.
- You will observe that the LED lights up as soon as the wires are hooked in! The experiment can be performed with a single potato as well, but the voltage generated is insufficient. This is why two voltages are connected in series to add them and generate more current.
When zinc comes in contact with copper, it loses its electrons, which are taken by copper. However, the electrons can only travel from zinc to copper in an electrolyte, an aqueous solution that contains a plethora of ions and facilitates the flow of electrons. Here a potato act as the electrolyte.
Chemical energy is converted to electric energy through a spontaneous electron transfer. The copper penny acts as the positive terminal of the battery and the zinc acts as the negative. This experiment can also power LED clocks.
2) Invisible Ink
Remember the scene where Nicolas Cage discovers a hidden message behind The Declaration of Independence in National Treasure? Before dismissing the scene as outrageous (or could it be, in fact, true?) one should know that George Washington’s army regularly utilized invisible ink to send secret messages during the American Revolutionary War.
The experiment depicts the implications of oxidation. The major ingredient we require to demonstrate it is a lemon.
- In a small bowl, mix one teaspoon of water and juice from one half of a neatly sliced lemon.
- Dip a Q-tip into this solution and write your message on a blank sheet of white paper. Let the ink dry for a few minutes.
- Bring a heated bulb or radiator close to the text and witness how the letters gradually come to life.
Lemon juice is composed of carbon compounds that are colorless at room temperature. The presence of heat breaks down these compounds and frees the carbon in them. When the fleeing carbon contacts the surrounding air, it becomes oxidized, causing the substance to become dark.
3) Film canister rocket
This is a lesson in rocket science, particularly a rocket’s fuel and its propulsion. Rocket fuel causes a rapid and exponential increase in pressure, such that the gushing gas propels them off the ground. Our fuel’s ingredients are a fizzing antacid tablet, such as an Alka-Seltzer and water, that’s all!
- Pour some water into an empty 35 mm plastic film canister. Unfortunately, nowadays, these are really hard to find.
- Step outside and put on your goggles to ensure safety.
- The next steps must be done swiftly:
- Put the tablet inside the can, close the lid and place it cap-side down on the ground.
- Step back at least 2 meters from the miniature rocket.
- After a few seconds, you’ll hear a *pop* and the canister will effusively launch into the sky!
The reaction between water and an antacid produces carbon dioxide, causing an increase in pressure inside the canister. As the pressure progressively increases, at a certain point, the can becomes unable to keep hold of its constituents and the film canister rocket blasts off into the air. One can make the experiment more intriguing by attaching some fins or cones to steer it in a more predictable path.
Actual rocket fuels implement something much more explosive, an extremely exothermic reaction between hydrogen and oxygen to form water. The resulting heat and pressure are used to thrust the rocket into space.
4) Invisible straw
This simple yet highly instructive experiment depicts the behavior of light as it passes through different materials. The experiment results in a bewildering optical illusion that highlights the effects of different refractive indices of different materials.
The apparatus includes a tall straw or licorice candy, a drinking glass and some cooking oil, such as olive oil.
- Pour the oil into the drinking glass.
- After submerging the straw or licorice into the glass you will notice that the straw’s appearance distorts, becoming wider or narrower.
- Lean the straw against the glass’s side by making a bend at its bottom to fix it at this position.
- Observe the straw’s appearance from the side as you turn the glass slowly. At one stage, you perceive the straw to be conspicuously cut in half as if it has magically disappeared from the bottom.
Light bends in water, which is why a water bottle is known to double as a magnifying glass. However, oil refracts light even more severely, so much that if the glass is observed at a particular angle, the other half of the straw is entirely hidden from our vision – it vanishes!
5) Elephant toothpaste
Along with potato power and household lava, elephant toothpaste is one of the most popular science experiments for kids that illustrates how amusing chemistry can be.
The experiment requires two containers, one large bottle and one small cup. You will also need hydrogen peroxide solution (ask an adult to purchase it from a beauty supply store or salon), some dry yeast, liquid dishwashing soap and food coloring for, well… aesthetics. Again, do not forget to use goggles to ensure safety, especially considering that hydrogen peroxide is known to irritate our eyes.
Perform the experiment on kitchen slabs or platforms that can be easily cleaned as the results, however magnificent, can be extremely messy.
- Pour a half cup of 20 volume or a 6% solution of hydrogen peroxide into the plastic bottle.
- Add one tablespoon of liquid dish soap and a few drops of food coloring.
- In the second smaller cup, add water and mix it with yeast for 30 seconds.
- Mix the contents of the smaller cup with the larger bottle and *boom* let the magic begin!
- You’ll observe a large thick paste spurting out of the large plastic bottle, like toothpaste oozing out of its container, a toothpaste for elephants!
The paste or foam contains thick bubbles that are filled with oxygen. The oxygen is produced by a rapid decomposition reaction of hydrogen peroxide (H2O2) catalyzed by yeast. The surge of oxygen is pushed out and trapped into the soapy water, creating foam and bubbles. Furthermore, the food coloring makes the display even more dramatic.
6) Blind spot
This experiment explores our neurology, particularly the structure and absurd behavior of our visual system. The blind spot is an area on the retina, our projector screen, that is devoid of receptors that respond to light. An image cast on this point cannot be viewed. It is the region where the optic nerve exits the eye and connects to the brain.
- On a blank piece of paper, draw a large dot and a large ‘+’ separated by 7-8 inches.
- Now, close your right eye and look at the ‘+’.
- Simultaneously, move forward toward the page such that at a certain distance the dot falls on the blind spot and it disappears!
- Perform the experiment by closing the left eye, observing the dot and obscuring the ‘+’.
Another peculiarity is that the brain fills a discontinuity that falls on a blind spot by using the data it gathers from generalizing the characteristics of its surrounding. Our perception is therefore literally based on assumption!
Consider this experiment:
Close your right eye and look at the carrot with your left eye. As you move your head closer, the discontinuity between the red strips disappears at a certain distance, such that now it is also perceived to be filled with red.
This absurdity is more evident in this picture:
Repeat the same steps and witness how, at a certain distance, the circle is run over by the lines around it!
Fire Bubbles and Exploding Toothpaste: More Unforgettable Experiments that Make Science Fun (Steve Spangler Science)