What\u2019s going on: <\/strong>The muscular system is made of special cells called muscle fibres that contract to help your body move. \u201cAs you crouch, the muscle fibres in your thighs, hips and glutes contract,\u201d MacKenzie says. \u201cWhen you start to jump, the muscle fibres expand, and the effect is like a spring uncoiling.\u201d That releases the energy needed for your body to jump. When your legs are straight, the muscles don\u2019t contract, so they don\u2019t release as much energy.<\/p>\n\n\n\n What to do: <\/strong>Have your child sit in a chair blindfolded, then stand up and spin in a circle seven times. Now, without removing the blindfold, have them try to find the seat to sit down. (Make sure you do this in a safe place that\u2019s clear of obstacles!)<\/p>\n\n\n What\u2019s going on<\/strong>: The nervous system relies on chemical and electrical signals to communicate with the brain and different parts of the body. Those signals are sent with the help of receptors that are all over your body \u2013 including hair-like structures in the inner ear. When those receptors are touched by the endolymph, a fluid inside the ear\u2019s canals, they send a message to the brain that your body is moving. But after you stop spinning, the fluid keeps moving.<\/p>\n\n\n\n \u201cThat sends signals to the brain, brain stem and cerebellum, and the brain interprets this as movement,\u201d says biology instructor Jamie Parker of Fordham University in New York City. \u201cSo, if the liquid is moving while you\u2019re still, your brain still thinks you\u2019re still spinning.\u201d<\/p>\n\n\n\n Get more fun family activities straight to your inbox with Nat Geo Kids’ free newsletter. Sign up here!<\/a><\/p>\n\n\n\n What to do: <\/strong>Fill an empty water bottle with water and dump it into a large basin. (Tip: Do this in the sink!) Refill the bottle, mark the water level on the outside and place the cap back. Turn the bottle upside down into the basin. Then, keeping the mouth of the bottle underwater, take off the cap. Have your child insert a bendy straw into the jug, with the other end sticking out of the water.<\/p>\n\n\n\n Have your kid take a deep breath, then blow into the straw until no more air is in their lungs. When they\u2019ve blown out all they can, place the cap back on the still-underwater jug. When you remove it from the water, you\u2019ll see the water level has gone down, and the missing water replaced by air.<\/p>\n\n\n\n What\u2019s going on: <\/strong>Our lungs breathe in oxygen that our cells need to live, then breathe out carbon dioxide as a waste product. The air in the bottle shows how much carbon dioxide they\u2019ve exhaled \u2013 and how much lung capacity they have to inhale air.<\/p>\n\n\n\n What to do: <\/strong>Have a child stick a marshmallow on top of a toothpick. (A mini one is best, but any will do!) With their arm palm-up on a level surface, balance the marshmallow so that the toothpick sticks straight up over their wrist where they feel a pulse. You\u2019ll see the marshmallow stick jiggle back and forth or even hop up and down. Then have your kid jog or do star jumps for 30 seconds, and repeat. The marshmallow stick will move faster!<\/p>\n\n\n What\u2019s going on: <\/strong>The circulatory system is what causes the heart to pump blood and lymph through your body\u2019s arteries and veins. Pumping blood into an artery creates a pulse. That\u2019s what you feel when you press your fingertips to your wrist\u2014and why the marshmallow stick moves when it\u2019s balanced there. And after you exercise? \u201cThe heart pumps more<\/em> strongly to send more blood to the areas of the body that are moving, bringing them more nutrients and oxygen,\u201d Parker says.<\/p>\n\n\n\n What to do: <\/strong>Grab a friend for this experiment! With a long string, Kid 1 measures the height of Kid 2, then cuts the string there. Then Kid 2 stretches their arms out to each side, and Kid 1 uses the same string to measure fingertip to fingertip. It will be almost exactly the same length!<\/p>\n\n\n\n Now fold the string in half, and measure from the bottom of the heel to the top of the femur (just under the rear end). It will be almost exactly half the distance from fingertip to fingertip. If you unfold the same string and then fold it in half twice, it will equal the distance from the elbow to the fingertip. Finally, unfold the string and refold it in thirds, and it will equal the circumference of the head!<\/p>\n\n\n\n What\u2019s going on: <\/strong>The skeletal system is all about the body\u2019s bones and how the muscles support them, helping us stand and walk. So, your skeleton\u2019s limbs must be proportionate to each other. “If these proportions are uneven, it will impact your gait,” MacKenzie says. If your legs are uneven, you might limp. Or, if your arms are too long for your legs or your skull is too big for your spine, you might have trouble balancing.<\/p>\n\n\n\n2. Spinning and Sitting (nervous system) <\/h2>\n\n\n\n
![\"one](\"https:\/\/cdn.creatureandcoagency.com\/uploads\/2023\/08\/EasyScienceExperimentsToDoAtHome-2.jpg\")
<\/a><\/figure>\n<\/div>\n\n\n3. Water Bottle Test (respiratory system)<\/h2>\n\n\n\n
4. Hopping Marshmallow (circulatory system)<\/h2>\n\n\n\n
<\/a><\/figure>\n<\/div>\n\n\n5. Bag of Bones (skeletal system) <\/h2>\n\n\n\n
Looking for even more easy science experiments to do at home? Check out our ‘magic’ experiments article<\/a>.<\/h2>\n\n\n\n
Written by Jamie Kiffel-Alcheh. Image credits: Girl jumping \u00a9 Halfpoint Images \/ Getty Images; Blindfold \u00a9 JGI \/ Jamie Grill \/ Getty Images; Marshmallow \u00a9 Shannon Hibberd \/ NG Staff.<\/strong><\/h6>\n","protected":false},"excerpt":{"rendered":"