real science for today's homeschooler

Cloud in a Glass

Cloud in a Glass

As you’re studying weather, take a few minutes to make a cloud in a glass to help explain the process of condensation and cloud formation.

What you’ll need: clear glass or jar, kitchen matches, ice cubes, small plate or pan that will completely cover top of glass or jar (metal works best), boiling or very hot water

Procedure:
1. Fill the plate or pan with ice cubes and have it ready to quickly place over the top of the glass when needed.
2. Pour enough boiling water into the glass or jar so that there is about 1/2 centimeter of water covering the bottom.
3. Light a kitchen match and hold it inside the top of the glass for a minute or so. Right before the flame reaches your fingers, drop the match into the water in the glass.
4. Immediately, cover the top of the glass with the pan containing ice cubes.
5. Watch a “cloud” form inside the glass!

What’s Going On?
The boiling water has enough heat energy to cause some of the water molecules to evaporate and turn into water vapor inside the glass. Those individual water molecules will stay in a gas state as long as they have enough energy. When the pan of ice is placed over the top of the glass, heat energy from the water vapor molecules is transferred to the bottom of the cold pan. The water vapor molecules no longer have enough energy to remain in a gas state, and they condense back to a liquid state. The smoke from the burning match is made of tiny particles which remain suspended in the air inside the glass. As the water molecules began to condense, they collect around the smoke particles, forming the tiny water droplets that make the “cloud” in the glass.

How do Real Clouds Form?
Clouds in Earth’s atmosphere form in pretty much the same way. As the Sun’s energy heats water on the surface of the Earth, it evaporates. As the moist air continues to heat up, it begins to rise higher into the atmosphere. Earth’s atmosphere gets colder and colder the higher up you go. When the water vapor in the rising air gets cold enough, it condenses around “condensation nuclei” in the atmosphere. Condensation nuclei are tiny particles of dust, salt, and other solids that are suspended in the air, similar to the smoke from the match. When enough tiny water droplets form in the atmosphere, we see a cloud in the sky!

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Using Popcorn to Practice Scientific Method

Using Popcorn to Practice Scientific Method

This is a fairly common science fair project that I actually helped my grandson carry out for an elementary science fair. It’s definitely not a new idea, but a great way to let children work through the scientific method using a fun topic . . . POPCORN! The question to be answered is: “Does storage temperature affect how well popcorn pops?” Children will be storing popcorn in a warm environment, room temperature, cold, and frozen. Before beginning the experiment, encourage students to make a Hypothesis. Ask them to decide which storage method they think will work best, and why.

Materials: large bag of loose popcorn (not the individual “flavored” bags), baggies, paper lunch sacks, access to a microwave

Here’s the procedure we used, but it’s important to let your child come up with the procedure if this is to be a scientific method experiment.

1. Put 100 popcorn kernels in a plastic baggie and label as “warm.” Repeat with 3 more baggies, labeling them as “room temperature,” “cold,” “frozen.”

2. Place the baggies in the appropriate area. For example, store the “warm” bag under an electric blanket, the “room temperature” bag in the pantry, the “cold” bag in the refrigerator, and the “frozen” bag in the freezer. Select a specific time for storage, such as a week, a month, etc.

3. After the storage time is complete, remove the bags from their storage area at the same time. To test the storage methods, divide out the 100 popcorn kernels between 5 paper lunch sacks, with 20 kernels in each bag. Label each paper sack with the appropriate storage method. Repeat with all the remaining popcorn, being sure to label each paper sack with the correct storage method!

4. Decide on a specific popping time. Somewhere around 2 minutes works best, but any time will work if it gives the popcorn time to pop and you keep the time the same for all trials.

5. Put one of each sack of popcorn into the microwave at the same time. (In other words, place one sack that contains popcorn stored as “warm,” one sack with “cold” popcorn, etc. Turn on the microwave for the specified time. After the time has elapsed, remove the bags and count the number of kernels that popped. Record. Repeat until all the popcorn has been tried.

Data: Here’s a sample data table that can be used to record the results. For older children you may want to let them design their own table.

  Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Average
warm            
room            
cold            
frozen            

 

Older children can find the average of each type. For younger children who may not understand the concept of averaging, change to “Total” for the last column.

Analysis: Younger children can compare the totals to see which storage method resulted in more popped kernels. Older children can graph the results for a visual representation.

Conclusion: Have students state out loud, or write down, which storage method produced the most popped popcorn. Why do they think this method worked best? Also have them refer back to their original hypothesis. Was their hypothesis right or wrong?

HINT: Based on experience, don’t try to pop one bag at a time in the microwave. There will not be enough water in the popcorn to absorb the microwaves and the appliance will overheat! Mine actually stopped working for awhile! Popping four bags at a time worked well for us, but do feel the sides of the microwave after the first round to make sure it isn’t overheating. Take breaks between rounds if needed.

ALTERNATE METHODS: Children can also come up with their own idea of what to test, such as light vs dark, storage time, type of storage container, etc. The more children are able to make the experiment their own, the better!

BACKGROUND: Depending on the age of your child, You may also want to have them research WHY popcorn pops. Here’s a great website that explains the science of popcorn, as well as some interesting history: http://www.popcorn.org/Facts-Fun/What-Makes-Popcorn-Pop.

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Water Conservation

Water Conservation

How many times do you have to remind your kids . . . “Turn off the water!” . . . or, “Turn off the light when you leave the room!” Kids are forgetful and they sometimes need help developing good conservation habits. Here’s a simple activity that will make your kids aware of how much water they can waste simply by brushing their teeth!

1. Find a large bowl that will just fit into the sink to collect water running from the faucet.

2. Have your child brush their teeth as they typically do, leaving the water running the entire time.

3. When they finish brushing and rinsing, measure the volume of the water collected in the bowl. You can use any measurement that works for the tools you have on hand. Cups might be the best, as you can convert your final measurements into gallons. Students have a good concept of how much a gallon is when they think about a gallon of milk.

4. Repeat the process, but this time, have your child turn off the water when they are not using it to wet the toothbrush, rinse, etc. When finished, measure the amount of water used.

5. Have your child subtract the difference between the amount of water used when running the faucet the entire time and when only turning it on when necessary. Convert to gallons: 1 gallon = 16 cups.

6. Finally, have your child calculate the number of times they brush their teeth in one year. Multiply by the amount of water that can be saved at each brushing. The amount of water wasted each year by letting the faucet run is surprising!

7. To extend for older children . . . multiply that amount of water by the number of people in your household to see how much water the family could save in one year. Then, help your child read a recent water bill to determine how much your utility company charges per gallon of water. Use that figure to calculate the amount of money your family could save by turning off the faucet while brushing your teeth!

Disclaimer: If you follow this project through to the very end, be ready for your child to transform into the “faucet police”! 🙂 Once children “see” the results of conservation techniques they do tend to become aware of what everyone around them is doing!

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Popsicle Science – Turn a Summer Snack into a Science Lesson!

Popsicle Science - Turn a Summer Snack into a Science Lesson!

Do you make popsicles for your kids during the summer? Involve them in the process and turn it into a science lesson!

Materials:

juice, plastic cup, ruler, waterproof marker, popsicle stick (or plastic spoon), index card

Procedure:

1. Fill a small plastic cup about ½ full of juice. (Cups with the straightest sides work best.)

2. Cut a slit in the middle of an index card and place it over the cup. Insert a Popsicle stick or plastic spoon through the card and into the liquid, holding it upright with the index card.

3. Make a mark on the outside of the plastic cup at the top of the juice.

4. Measure the height from the bottom of the cup to the mark. Record.

5. Place the cup in the freezer and leave undisturbed until frozen.

6. Remove from the freezer and measure the height of the frozen juice. Record.

7. If age appropriate, calculate the change in height and record.

8. Ask the question, “Why is there more juice in the cup when it is frozen?”

How it works:

Juice contains a large amount of water. Water is one of the only substances on earth that expands when it freezes. Most liquids contract as they get colder as the molecules slow down and get closer together. Water does contract as it cools all the way down to 4°C. But between 4°C and 0°C (the freezing point of water), the water molecules actually begin to spread farther and farther apart. Solid water (ice) is less dense than liquid water because the molecules in ice are spread farther apart than in water. That’s why ice floats in water.

 

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