When trying to think of fun experiments to do in homeschooling, one major factor was accessibility of equiptment. Let's face it, I'll never be able to teach them the microbiology I learned in college as we don't have the equiptment necessary to perform the experiments safetly. So I try to make experiments that still prove the hypothesis but use basic things we already had around the house! Furthermore, I have kids that are several years apart in ages. So most of my experiments need to be able to span those cognitive differences. Many of these experiments have a single step or explanation that can be changed slightly for older kids - but as with everything else on this site, it's sufficient for kids ranging from Preschool - about 7th grade.
Most science projects usually need the following:
Mento's & Soda Geyser: The droping of Mentos into a carbonated soda results in the soda exploding out of the bottle as the carbondioxide (gas) is rapidly released.
How to do the experiment:
Useful References:
MadSci Answer: What is the chemical equation that occurs when mixing soda and mentos?
Buoyancy:
What is buoyancy? It's the force of water pushing up on something. Sometimes it's enough to make things float, sometimes not. How does it work?
Equipment:
Safety:
1. Don't drink the water - the bucket and rocks will make it dirty.
2. Don't get your mom or dad wet without asking first!
How to do the experiment:
1. Go outside and fill up the bucket with water.
2. Put the rocks, one at a time, in the water. (We put them in one at a time because we are polite, and also because it is important to keep all the water inside the bucket.) Do they float?
3. Take the empty jar, close the lid tightly and put it in the water. Does it float? If it doesn't, get another jar... Empty jars are supposed to float.
4. Take the rocks out of the water. Put the smallest one in the jar. Close the lid and put the jar back in the bucket. Does it still float?
5. One rock at a time, add more of the rocks to the jar. Each time you add one more rock, put the lid back on and see if the jar still floats.
If you can fill the jar with enough rocks, you will eventually be able to make it sink. Why?
Why do rocks float when they are in the jar, but sink if they are not?
Explanation:
Everything in or on water pushes some water aside, even if just a little bit. This is called displacement.
The smallest rock sank, didn't it? When it did, it had to displace some water to make room. The water level went up a little when this happened. If we could weigh the little rock and the amount of displaced water, we would see that the rock weighs more than the water, since it sank right to the bottom of the bucket! Next, lets say we weighed our jar with the smallest rock inside and the amount of water IT displaced. Our jar with the little rock floated, didn't it? On our scale, it would weigh THE SAME as the water it displaced. If we kept weighing our jar with more rocks, and the water it displaced each time, we would see that the jar displaces more and more water. The heavier the jar gets, the more water it displaces, but as long as the two weights are the same, the jar will still float. At some point, the jar begins to be heavier than the water it displaces, and this is when it finally begins to sink.
When you made the jar heavy enough sink, were you able to see the water level in the bucket rise?
Liquids vs Gasses:
A fun way to demonstrate the fact that liquids are nearly incompressible while gases are quite easy to compress.
Equipment:
How to do the experiment:
Goes as follows :
Fill the jar or widemouth bottle with water almost to the top, but leaving 2-3 cm of air above water level. Put the small vial in the bottle or jar in such a manner that the mouth points down, and carefully flood the vial with water almost but not completely to the top so that the vial *barely* floats.
Cut the party balloon open and close the mouth of the jar or bottle with a piece of rubber, securely attach the rubber by tying the rubber around the neck of the jar or bottle with a string (tightly !) so that the mouth is completely covered with a rubber diaphragm.
Now, press on the rubber with a finger and observe. If everything has been done properly, the little vial will gently sink to the bottom on the bottle as you press on the rubber and will immediately float up as you release the pressure. Experiment is repeateable ad infinitum or, at least, while the rubber holds.
Non-Neutonian Liquids: Combined in just the right proportions, a mixture of corn starch and water makes a slimy-yet-firm goo.
Equipment:
Corn starch, water, container, stirring rod, measuring spoon.
How to do the experiment:
Combine a handful of corn starch with a spoonful of water. Stir, and add more water if the substance seems too crumbly. Properly mixed, the substance should seem liquidy on top. Poke it with your finger to make sure. Now pour a little into your hand, squeeze, and release. Have fun, but if the ooblech seems to be drying out, add a little more water.
Explanation:
The forces of attraction between the starch molecules and the water vary with the amount of applied pressure. When are the attractive forces strongest? When are they weakest?
Useful References:
Non-Newtonian Fluids (MadSci Archives).
Or try running a search for Non-Newtonian, fluid on the MadSci Search Engine.
Once your students have a basic understanding that things are either a liquid, solid or gas; and the processes that can change something between these states of being (ie heating/cooling) then they're ready to move onto to thinking about what happens when we combine matter.
Making Butter:
Directions:
What Happened?
Why does the process of making butter depend on the fat molecules suspended in the liquid?Cream is an emulsion of fat in water. The fat droplets are held in suspension by the milk protein. When you make butter from cream, you force the fat droplets to join together.
This process is called coalescing.
Consumption:
Milk into Plastic? Many plastics are made from petroleum oil. You can make a similar, simpler plastic using milk and vinegar.
You Will Need:
Directions:
Making Slime!:
Equipment:
Safety:
Not to be fed to your pet or baby brother. Not good for leaving in carpets or on furniture overnight. To keep almost indefinitely, leave in ziploc bag in refrigerator when not sliming! Not a bad idea to wash hands before (so it doesn't grow mold) and after (so mom will let you eat dinner) playing with it.
How to do the experiment:
Homemade Slime Recipe
1. Take a cup of water and add to it 1 Tbs. of borax (approx 4% solution). Stir until completely dissolved.
2. Make a 50% water 50% white glue solution. Take 1/4 cup of each and mix thoroughly.
3. In a ziploc bag, add equal parts of the borax solution to equal parts of the glue solution. 1/2 cup of each will make a cup of slime.
4. Add a couple drops of food coloring.
5. Seal bag and knead the mixture.
6. Dig in and have fun. Remember to wash your hands after playing.
7. Keep your slime in the sealed bag in the refrigerator when not playing with it to keep it longer. Unfortunately it may eventually dry out or grow mold. Just throw it out and start again!
Explanation:
The borax is acting as the crosslinking agent or "connector" for the glue (polyvinyl acetate) molecules. Once the glue molecules join together to form even larger molecules called polymers, you get a thickened gel very similar to slime. If you've tried this recipe (formula) before using blue starch (instead of the borax) with mixed results, you won't be disappointed with this one. Works everytime! If you have access to a chemical supply house, try a 4% solution of polyvinyl alcohol instead of the glue for a less rubbery polymer and one that is transparent showing off the color better.
Tectonic Plates/ Earth Quakes/ Fault Lines: My kids LOVED this experiment as it really gives a clear idea of what's occuring far below our feet. There are actually 3 different experiments combined here to understand the stressors placed on our fault lines.
Experiment 1: The Destruction of a Plate - some plates will overlap, one plate folding under the other being pushed ever downward into the hot molten level of the mid layer of the earths crust thus disolving the plate into more molten rock. This experiments sees what the pressure of being forced down does on the plates weak spots.
Experiment 2: Opposite forces - Some plates are being pushed in opposing directions (one up and one down). Where they rub together builds and builds pressure until the strength of the kinetic energy causes crumbling (an earth quake). This experiement shows that happening.
Experiment 3: Inward forces - sometimes when two plates push toward each other one doesn't go under while the other goes over (as in experiment 1) sometimes the plates will buckle and both shoot up into the sky - creating new mountain range volcanoes. This experiments shows what damage is done to the plates as they press ever toward eachother just before pushing upwards.
Experiment 4: Fault Lines - this experiment shows how fault lines occur, and what they look like, using American Cheese (I like using several different kinds of cheese to represent the different kinds of stone) - ask the students to think of topographical identifiers that might be mistaken for a fault (like the Grand Canyon which isn't formed of a fault but of water carving through the rock)
When you pull on a piece of cheese, you are creating tensional stress throughout the volume of the cheese. If there is a defect in it (like the incision you made), the stress cannot be transmitted across that defect (the walls of the incision can't pull on each other), so the stress that would normally be transmitted across the defect is instead concentrated around the edges of the defect. To visualize this, try drawing a square like your piece of cheese, and then draw evenly spaced lines from one side to the other, parallel to the direction you are pulling. Don't let any of the lines cross the fracture...instead, make them curve around the nearest edge of the fracture. The concentration of lines you get around the edges of the fracture represents the concentration of tensional stress. This concentration of stress means that the cheese will want to split apart around the edges of the incision. The bigger the fracture gets, the more stress will be concentrated at the tip of the fracture. This is why it gets easier to pull on the cheese as the fracture grows. When the tips of two fractures go past each other, the direction of tensional stress that the fracture tips "see" changes because the stress cannot be transmitted in a straight line across that gap; it is curved around by both of the fracture tips. To visualize this, try drawing the piece of cheese as it looks as the fractures start to bend. Draw the lines across it as you did before, and see how the stress direction is bent between the fractures. This is what makes the fractures bend toward each other and link up into a larger "fault."
Overview:
Make a simple compass to find magnetic north, or south, depending on where you live.
Equipment:
1. Sewing needle ~1 inch (3cm?) long.
2. Small bar magnet. Refrigerator magnets may work if you don't have a bar magnet.
3. A small piece of cork.
4. A small glass or cup of water to float the cork and needle.
How to do the experiment:
1. Your compass will work better if you first run a magnet over the needle a few times, always in the same direction. This action 'magnetizes' is to some extent. Drive the needle through a piece of cork. Cork from wine bottles works well. Cut off a small circle from one end of the cork, and drive the needle through it, from one end of the circle to the other, instead of through the exact middle - be careful not to stick yourself!
2. Float the cork + needle in your cup of water so the floating needle lies roughly parallel to the surface of the water.
3. Place your 'compass' on a still surface and watch what happens. The needle should come to point towards the nearest magnetic pole - north or south as the case may be.
4. If you want to experiment further, try placing a magnet near your compass and watch what happens. How close/far does can the magnet be to cause any effects?
Explanation:
The earth produces a magnetic field. This field, although weak, is sufficient to align iron and other paramagnetic compounds such as your needle within it. By floating the needle on the cork, you let it rotate freely so it can orient itself within the earth's magnetic field, to point toward the north or south poles of the planet.
There are several experiments that include the basic chicken egg:
Peeling a Raw Egg:
Directions:
What happened?
Vinegar contains a weak acid, acetic acid, which reacts with the calcium carbonate in the egg's shell.Over time, the acid "eats" the shell away, producing small bubbles of carbon dioxide gas, which can be seen around the egg. When the bubbles stop appearing, the reaction has finished.
The Strong Egg - the curved arch of the eggs design is actually the basis for the 3-dimentional arch in architecture - one of the strongest architectural forms!
Squeeze an Egg Without Breaking It
Eggs are amazingly strong despite their reputation for being so fragile. Place an egg in the palm of your hand. Close your hand so that your fingers are completely wrapped around the egg. Squeeze the egg by applying even pressure all around the shell. To everyone's amazement (mostly your own) the egg will not break. If you're a little nervous about the outcome, try sealing the raw egg in a zipper-lock bag before putting the squeeze on it, or hold the egg over the sink if you're in the super-brave category.
Why didn't it break? The curved form of the shell distributes pressure evenly all over the shell rather than concentrating it at any one point. By completely surrounding the egg with your hand, the pressure you apply by squeezing is distributed evenly all over the egg. However, eggs do not stand up well to uneven forces which is why they crack easily on the side of a bowl. Be careful not to wear a ring while performing our squeezing act. The uneven pressure of the ring against the shell will result in an amusing display of flying egg yolk for your audience members. -- THis is a great experiment for demonstrating force!
Are You an Egg Psychic? Yup, you are. You can tell if an egg is hardboiled or raw with nothing more than a spin.
Hardboiled or Raw?
The answer is only a spin away. Simply spin the egg and pay close attention to how well it spins. If the egg spins well, it's hardboiled. However, if the egg wobbles and spins slowly, it's the raw one. A hardboiled egg is solid inside whereas a raw egg is fluid. When you spin the raw egg, its center of gravity changes as the fluid inside the egg moves around. This results in the wobbling motion you noticed in the raw egg. As soon as the raw egg starts spinning, touch it briefly with your finger just long enough to stop it. When you take your finger away, the egg will continue to spin for just a quick second. This is due to the inertia of the fluid inside the egg. When the hardboiled egg is spun, the solid center immediately moves with the shell, causing little resistance to the spinning motion.
Another test of Hardboiled or Raw? Does it float?!?! It's so simple and amazing. A raw egg will float in very salty water but will sink in plain tap water. Why? Salt water is more dense than regular water. You'll need to make a very saturated salt solution by dissolving roughly 4 tablespoons of salt in about 2 cups of water. Use pickling or Kosher salt to make a clear salt solution. Table salt may be used, but the solution will be somewhat cloudy due to the additives used to make the salt free-flowing.
Fill a glass half full with the salt water. Slowly add plain water by pouring it down the sides of the glass being careful not to mix the two liquids. Gently drop the egg into the water and watch as it sinks through the plain water only to abruptly stop when it hits the salt water. It's amazing to see how the egg floats on the top layer of the salt water (even more amazing if you don't know about the bottom layer of salt water!).
The Magickal Floating Egg:
Fill the bottom 1/5 of a tall glass with salt. Add just enough water to make a wet salt layer. Carefully lower an egg down on top of the wet layer of salt. Slowly add more water by pouring it down the sides of the glass so as not to disturb the bottom layer of water. Cover the top of the glass with cellophane and a rubber band. Notice how the egg rests on the layer of undissolved salt on the bottom of the glass.
Over the course of the next several weeks, the bottom layer of salt will begin to dissolve in the water above it. As the salt dissolves, the egg will rise off the bottom and float on the layer of salt water. As more time passes, the salt level continues to drop and the egg continues to rise. Be sure to put this the glass in a place where no one will be able to disturb it. You can even record the egg's progress by marking on the outside of the glass using a felt tip marker. Remember, this process is supposed to take a long time (months!) which is why it is so interesting.
You might wish to substitute a golf ball in place of the egg to avoid the decay of the egg's shell over time. The "golf ball" idea was originally published by Bob Becker, a great chemistry teacher from St. Louis, Missouri.
Most children decorate eggs for Easter, but here's a way to get in a little science experiment with your decorating. Is it possible to actually etch an egg without breaking it? We have found the answer.
1. Draw on your egg with the crayons. You create designs, write words, or even just scribble. The color of the crayons doesn't matter. Be very careful not to crack the egg when you are writing on it.
2. Put the egg into the widemouth jar and cover it with white vinegar.
3. Let the egg stand in the vinegar for two hours and then pour out the vinegar and replace it with fresh vinegar.
4. Let the egg stand in the fresh vinegar for another two hours, then take it out of the jar. Wash the egg and remove all the crayon markes. This will create an etched egg shell.
The crayon acts as a protective barrier to the vinegar. The acid in the vinegar dissolves much of the calcium carbonate of the eggshell. The wax in the crayons protects the parts of the shell that you wrote on and keeps it from dissolving.
Egg In A Bottle
Kids never cease to be amazed by this little trick, no matter how many times you show it to them.
1. Set the egg on the neck of the bottle to demonstrate that the egg simply won't fit in the bottle. Tell the child that you know a trick to make that egg go down into the bottle without breaking it.
2. Remove the egg from the bottle and pour the boiling water into the bottle. Carefully roll the water around in the bottle and then pour it out.
3. Quickly put the egg back on the neck of the bottle and wait for it to get sucked down into the bottle.
The Explanation
When you put the hot water into the bottle and then poured it out, the hot water left steam behind in the bottle. The steam forces out some of the air that was already in the bottle. As the steam in the bottle cools down, it converts into tiny droplets of water. The drops of water require less space and this reduces the amount of air pressure in the bottle. The pressure on the outside of the bottle is greater than the pressure on the inside of the bottle and that is what forces the egg into the bottle.
You can remove the egg from the bottle using the same process in reverse. Hold the bottle upside down and blow into the bottle for about 30 seconds. Be sure to seal your lips around the mouth of the bottle when you do this. By blowing into the bottle, you will increase the pressure on the inside of the bottle and force the egg out.
Some dyes act as indicators - they change colour depending on whether they have acid or alkali mixed with them.
You Will Need:
Directions:
Testing the Indicator:
What happened?
The bicarbonate of soda or ammonia (alkalis) should have turned the cabbabge water a pale greeny-blue. The vinegar or lemon juice (acids) should have turned the cabbage water a reddish colour.The red cabbage dye is behaving as an indicator, a chemical substance which changes colour, depending on the acidity, or alkalinity of its environment
Lemon Fizzy: see how the acid of the lemon reacts to the base in the carbon dioxide
Directions:
Questions to Ask:
Consumption:
Baking Soda Volcano:
Create quite a fizzle by mixing baking soda/sodium bicarbonate - a base with vinegar/acetic acid. Well.. it's theoretically 'edible' but I wouldn't recommend tasting it (yuck!).
Equipment:
1. Baking Soda - Make certain the box says 'soda,' and not 'powder.'
2. Vinegar
3. A container to hold your reaction. In 4th grade we made a plaster of Paris volcano with a well in the middle to hold the 'reagents.'
4. paper towels, depending on the extent of mess you plan to make.
Safety:
Though the reagents are harmless, it might be a good idea to take precautions to make sure the stuff bubbling off doesn't get in your eyes.
How to do the experiment:
1. In a container place some of the baking soda.
2. Pour in some vinegar
3. Watch what happens.
The Lemon or Potato Battery: Batteries contain a chemical called an electrolyte, which allows a chemical reaction to occur between the electrodes, which creates electricity. Lemon juice will act as an electrolyte.
You Will Need:
How to do the experiment:
What happened?
The juice of the lemon/potato acts as an electrolyte, similar to the contents of a battery. By using two different types of metal, one the anode, the other the cathode, electrons flow through the electric wire, via the light bulb, from one metal to the other. This causes the bulb to light!
Try the effect with different fruits and vegetables. How well do other citrus fruits or tomatos work? If using potatoes, how does the size of the fruit or vegetable relate to how long the bulb stays lit? Does the pH of the vegetable relate to the amount of electricity generated? Lastly, what is the maximum Watt lightbulb you can light from your food battery? Try using some electricity equations to calculate parameters such as resistance, voltage and current.
Safety:
If no copper electrode is used, hydrogen gas is given off as a byproduct of the reactions taking place. Be wary of performing the experiment near heat sources or an open flame.Though the voltages and amperages given off are low, care should be taken in handling the wire and other parts of the circuit.
Mechanical Energy for Lighting when thinking of alternative forms of energy, not everything is about what type of equiptment you use, sometimes it's all about motion! Here chewing causes light!
Need:
Wintergreen Lifesaver candy (no other flavor will work).
Safety:
To prevent accidental choking on the candy pieces, have a glass of water handy to drink.
How to do the experiment:
Triboluminescence is the mechanical generation of light. Certain chemical bonds will generate light energy when the molecules are torn apart by mechanical crushing. Wintergreen Lifesaver candies contain some of these bonds. No other flavor of lifesaver candy (such as peppermint) will work in this experiment.
Each time a part of a Lifesaver is chrushed by your teeth you will see one or more flashes of white light in your mouth! Each piece of candy can produce many flashes of light as it is chewed and crushed.
Explanation:
You are generating light energy by triboluminescence because each time you chew the candy your teeth are tearing apart the chemical bonds that where formed when the liquid candy was molded into a solid lifesaver. Wintergreen contains molecules that exhibit triboluminescnece.
Automotive scientists are studing triboluminescent flashes as a way to sense automobile crashes so that the air bags can be inflated. Imagine having your life saved by a Lifesaver candy!
Here are some of the activities and such I used when studying the Human Body with my toddler: