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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Growing Crystals with Common Chemicals

Growing Crystals with Common Chemicals

Crystal growing is a fun activity for kids and it is relevant to several areas of science, such as chemistry, as well as mineral formation in geology. Schools often use commercial chemicals to grow crystals in the classroom, and these chemicals can be difficult, if not impossible, to purchase as an individual. Here are a few household chemicals that can be used to grow crystals at home:

Aluminum potassium sulfate (alum) can be purchased in the spices area of the grocery store. This alum is not pure, and crystals do sometimes turn out small. Purchasing a more expensive brand will often grow better crystals, but alum is fairly expensive.

Sodium borate (borax) can be purchased in the laundry section of many stores.

Calcium chloride can be purchased at home improvement stores and stores that sell chemicals for swimming pools. Even at a specialty store, this is a fairly inexpensive chemical to purchase.

Copper sulfate is the ingredient in products used to kill roots in sewer lines. You can find this at home improvement stores. Moderately expensive, but a container goes a long way. This chemical makes very large, beautiful blue crystals and is a favorite for crystal growing. But, do be careful with storage of the crystals as the chemical is poisonous and it can be mistaken for candy by young children!

Magnesium sulfate (epsom salts) can be purchased at a drug store or the pharmacy section of the grocery store. It’s fairly inexpensive.

Sodium chloride (table salt) grows very nice cubic crystals.

Sucrose (table sugar) is used to make “rock candy” crystals. There are quite a few recipes on the internet for making rock candy, and it is a favorite to make. However, these are the hardest crystals to grow, and it can be messy! I’ve tried this using several different methods and have never been very successful. If anyone has a good recipe and growing technique for making rock candy, please post! 🙂

How to grow crystals:

The trick is to make a supersaturated solution of the chemical. It’s best to start with distilled water, which can be purchased by the gallon at the grocery. Heat the water, slowly add the chemical, and stir until completely dissolved. In order to make a supersaturated solution, the water needs to be very hot and you have to dissolve as much of the chemical as possible. Continue to add the chemical a little at a time, dissolving thoroughly before adding more. When you finally reach the point where no more chemical will dissolve, pour the hot solution into the container you’ll use to grow the crystals. You can also add a little food coloring if you want to make colored crystals. Don’t add too much as you don’t want to dilute the solution.

It’s important to use a container with very smooth inside surfaces, like glass. Also, be sure to only pour in the solution that is completely dissolved. Let the undissolved chemicals settle to the bottom of the original container and don’t transfer the last bit of solution. Finally, suspend a string into the crystal growing solution to give your crystals something to grow around, and leave undisturbed. Depending on the chemical used, crystals usually begin to form within hours, but may take several days to grow larger.

Safety:

Take care with the finished crystals and store them appropriately. Copper sulfate crystals are especially poisonous if ingested. Whatever chemical you use, do read the product label for safety precautions. The same precautions should be taken with the finished crystals! Remember, many candies are made to look like crystals and small children may not be able to tell the difference.

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Separating Colors with Chromatography

Separating Colors with Chromatography

What is Chromatography?

Chromatography is the process of separating a mixture into its individual components. The easiest way to show this process to children is by using chromatography to separate inks. Waterproof inks in permanent markers and ball point pens require a chemical solvent, but the ink in washable markers can be separated with water, making for an easy and safe experiment.

Materials:

washable markers, coffee filters, pie pan

Procedure:

1. Flatten a coffee filter so that it can be written on.

2. Using washable markers, put small dots of different colors around the outside of the filter, about ½ to 1 inch from the outside edge. (Smaller dots work best. It is hard for the colors to really separate if there is too much ink on the paper.)

3. Put water in the bottom of the pie pan, using just enough to cover the bottom completely.

4. Arrange the filter so that it is back in its original shape with the pleats all neat, etc.

5 Place the filter upside down into the pie plate so that the outer edges are in the water. (It is very important that the dots be above the surface of the water in the pan. If the dots touch the water, the ink will dissolve into the water and the chromatography won’t work!)

6. Allow the water to creep up through the filter. As the water reaches the dots, the ink will begin to spread out and separate. This will take some time, but eventually the water will reach the top.

7. When the filter is completely wet, carefully remove the filter and allow it to dry.

8. Examine the results to see which colors make up each of the inks tested.

How it works:

The process of using paper chromatography to separate inks is pretty simple. Most colors of inks are actually made of more than one pigment, or color. Each of those pigments has different properties. Some are heavier than others. When a solvent passes through the ink, it picks up the different pigments and begins to carry them along. The lighter the weight of the pigment, the faster and farther it will travel. As each pigment continues to travel at a different speed, they become separated from each other, allowing you to see the individual colors that make up the original ink.

 

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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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