Catch a Raindrop

Mix 2 parts of flour with 1 part of salt. 

Fill a shallow pan with about half an inch of the mixture. 

On a rainy day, hold the pan outside for a few seconds.  (Or you could let water drip from your hand into the pan, but going out in the rain is more fun).

Let it sit, undisturbed for a few hours (or until the next day).

Use a fork to carefully remove the wet spots.  Set them on a plate to dry.

After they're dry, examine their shape and size.  Why do they look like balls and not like a "raindrop" shape?

You may want to try this on a variety of days - a day when it's barely raining, a day when you have a steady shower, and if you dare, a day when you have a downpour.  What similarities and differences do you observe between the raindrops collected on each of these days?

Older students could measure each of the drops they collected and then analyze the data; graph it, determine the mean, median, and/or mode. 

Exploring Water with a Pipette

Small children, kindergarten and 1st grade students (and even some preschoolers) can be taught to use a pipette.  This activity is a great way to have those young students learn about water, use a pipette and have some fun.  Older students will enjoy the activity as well (rooms full of teachers will enjoy it too). 

Provide each student with the following set-up:

A paper towel with a piece of wax paper on top of the towel.  A small cup of water and a pipette next to the wax paper. 

Begin by showing students the pipette, naming the bulb and stem. 

Walk students through the process of using a pipette:

--Squeeze the bulb

--Place the stem in the water

--Release the bulb

--Remove the stem from the water

--Squeeze the bulb a small amount to release a drop of water. 

Guide the students through the following exercises:

--Make a single drop on the wax paper.

--Use the pipette to pick up the drop of water.

--Move the drop of water around the piece of wax paper.

--Make 2 or 3 drops of water on the wax paper and push the drops together.

--Split the drop of water into smaller drops.

--Make a picture using drops of water (a face, for example).

Without even trying, the students will learn a lot about the nature of water by observing the shape of the drops, watching the drops come together, and struggling to separate the drop into smaller drops. 

With older students, you'll discuss adhesion, cohesion and surface tension, maybe even mentioning Hydrogen bonds. 

With younger students you'll discuss what you saw happening and the general idea that the water likes to stick to itself. 

If your students are on a roll with this activity, here are a few extentions you can use:

1. Have the students make drops of oil and/or rubbing alcohol on the wax paper.  Guide them through the same exercises and above and see if these liquids behave in the same manner as water.
2. Have students make their drops of water on other materials: paper towels, aluminum foil, plastic wrap.  How does the water behave on each of the surfaces? 

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Activity from Linda Burroughs, The College of New Jersey, presented at the 2010 New Jersey Science Teachers Association Convention



Water: Beads of Color

Place a thin layer of baby powder on a small plate. 

Place several drops of food coloring on the powder and observe the drops. 

The drops form a sphere, as the water molecules would rather cling to each other than to the baby powder.

Now, dip the end of a toothpick in some liquid soap.  Touch the soapy end of the toothpick to the food color beads.  Observe.

The beads spread apart because the soap interferes with the bonding that occurs between the water molecules.

Who Dirtied the Water

Who Dirtied the Water is an excellent activity found in the Access Excellence Fellows Collection.  

In short...

...you begin with some nice clean water from an undisturbed lake.  Beavers come and add some wood chips to the lake and a river washes sand into the lake.  People begin to settle the area and their waste enters the lake.  Soil from farm fields washes into the lake.  Eventually a city grows there, with houses, laundromats, factories, etc.  Each of these new additions adds something to the lake.  

As you read the story, students come and add the material to the water.  Periodically throughout the story, you ask the students if they'd want to swim in that water, eat fish caught in that water, or boat in that water.  

It's a powerful demonstration of what can happen to a water source over time.  And it's great for staring a discussion.  Students will have all different ideas of how dirty is too dirty.  And at the end, you get to the big questions - who made the water dirty and even bigger - who's responsible for cleaning up the water.  

It's a fantastic activity.  I most recently used it as part of the local library's summer reading program.  Since there were young (preschool) children taking part, I made a few changes.  

I made a name tag for each part, which contained a picture as well as the name.  The film canisters were labeled with pictures that matched those on the name tags.  These modifications made it more meaningful for children who are not yet reading, as well as making it easier for them to participate. 

For a nice progression of activities, start with Earth Ball Catch (land vs water on Earth), then do Earth's Water Necklaces (salt water vs. fresh water on Earth), and then do Who Dirtied the Water (take care of the tiny amount of fresh water available).

Magic Loop

Cut a length of thread or string about 30 cm long.  Tie it into a loop.

Place the loop on the table and try to form a circle with it.

Fill a pie plate with water and place the loop on the surface of the water.

Place a drop of dish soap in the middle of the loop and watch.

The loop forms a circle on its own*!

The soap lessens the surface tension in the middle of the loop, but the tension outisde the loop are still at full strength and pull on the thread from all directions.


*You have to be watching carefully to see the circle as it's a fleeting thing that can't be repeated without dumping the water, scrubbing the pan and starting again (once the soap breaks the surface tension, you can't put it back together again).  You have to act even faster if you want to get a picture of the perfect circle... 

Earth's Water Necklace

I use this as a follow-up to ProjectWET's A Drop in the Bucket* demonstration.

Each student will need:
-97 blue beads
-2 white beads
-1 green beads

Students string their beads onto a length of lanyard lacing.  They can string them in any order - I happen to prefer the symmetric approach, but the white and green beads can be placed anywhere on the cord.

The beads represent all the water on the planet.  The blue beads are salt water.  The white beads are frozen water.  The green bead is liquid fresh water. 

It's a great visual reminder of how precious a resource fresh water is.  I've done this activity with students as young as preschool (I count out the 97 beads for them) and as old as 6th grade. 



*You start with 1000 ml of water - that's all the water in the world.  Pour out 30 ml.
970 ml are salt water.  30 ml are fresh water.
From the 30 ml, pour out 6 ml.
24 ml are ice.  6 ml is liquid fresh water.
From the 6 ml pick up 1 ml.
5 ml are unusable (pollution, etc.).  1 ml is usable water.

So in summary:
970 ml - salt water
24 ml - trapped as ice
5 ml - polluted or otherwise unusable
1 ml - water usable for human consumption

Boat Races

Cut out a boat shape from an index card or piece of thin cardboard.

Cut a small notch out of the back of the boat.

Float the boat in a tub of water.  What happens?  Not much!

Now, place a small sliver of soap in the notch and watch.  What happens?  The boat moves across the tub!

Why?
Without soap, the water pulls on the boat from all directions, resulting in little to no movement.  When the soap is added, it reduces the pull of the water at the back of the boat.  The pull at the front of the boat remains  strong and you see movement. 

Students can experiment with boat shape to find the fastest (and straightest) racer!

Because the soap reduces the water's surface tension, the water in the tub will need to be dumped out and replaced often.

Static Electricity: Bending Water

This is one of the coolest demonstrations I've seen in a while... 

Rub a balloon along your hair about a dozen times. (You'll know it's enough if the hair on your arm stands up when you bring the balloon near it).

Turn on the faucet so you have a very small stream of water.

Hold the balloon near the water (but don't touch the water with the balloon).

Your hair charged the balloon with negative charges.  These attracted the positive charges in the water, causing the water to move.

The picture doesn't do it justice - you really need to try this one yourself!

You could also use a rubber comb instead of a balloon.  But, I found that the balloon worked even in really humid weather, and the comb didn't.

Modeling the Water Cycle

You'll find many variations of this activity, some more sophisticated than others, throughout the Internet and in numerous books.  This one is very basic - it's simple to set up and can be effective in helping students visualize the processes occurring throughout the water cycle.

You'll need a glass jar with a metal lid.

Fill the jar with about an inch of hot tap water (the hotter it is, the faster you'll see something happening). 

Flip the lid upside down and set it on top of the jar.

Fill the lid with ice cubes.

Wait, watch and observe.

The hot water will evaporate.  As it rises, it will cool.  The cooled vapor will condense into drops, which will accumulate on the underside of the lid and eventually drop.

Capillary Action in Action

You'll Need:
Water
Food Coloring
Overhead transparency* (You can use one that's been printed on that you no longer need, as I did)
Paperclips
Small, shallow dish (or a jar lid works)

Cut the transparency in half.  Stack the two pieces on top of each other, roll them into a tube and paperclip at each end.

Place some water in the shallow dish.  Add several drops of food color (don't use yellow for this demonstration, you need something darker to show up).

Stand the tube you made in the dish of liquid and watch what happens.  You may want to roll up a piece of plain white paper and slip it inside your tube to improve visibility.

As you watch, you'll see the colored water creep up the tube.  You're seeing evidence of adhesion - water's desire to stick to things other than itself.  So much so that it overcomes gravity to keep working its way up the tube. 

Didn't photograph real well, but the color did make it all the way up the tube. 

*Does my knowledge and use of transparencies make me old?  I feel like all the new teachers out there are laughing at me and my out-dated ways.  That no one uses an overhead any more, they all project things using their computers and SmartBoards.  Regardless, don't get rid of your overhead projectors, there are cool science demonstrations you can do with an overhead that you can't do with your fancy computers!  :)

Balancing Act

If you drop a paperclip into a cup of water, it will sink to the bottom, because paperclips are more dense than water.  But, if you're careful, you can take advantage of water's unique properties and make the paperclip "float" on the surface.  

Fill a cup with water - the fuller the cup, the easier to do this.

Use a fork to gently place a paperclip on the water's surface.  You want to place the whole paperclip on the water at one time.  You don't want one part of the paperclip poking through the water. 

This definitely takes some practice and can be a test of patience.  I have never been able to get more than one paperclip to rest on the surface of the water, but I've seen others do multiple paperclips at the same time. 

If you get frustrated watching someone else get their paperclips to stay on the surface while you can't, place a drop of soap in thier water while they're not looking...


Water molecules like ot stick to one another, creating a membrane-like surface across the top of the water.  If you place the paperclips just so, that strong surface tension will support the paperclips (they aren't actually floating - they are still more dense than water).  Soap breaks water's surface tension, so you won't get soapy water to support anything. 

Milk Fireworks

Pour enough milk into a pie plate to cover the bottom.

After the milk has stopped moving, place drops of different colors of food coloring in the milk.

Dip a toothpick in dish soap and then touch it to the middle of the milk.

Why:
The food coloring mixes with the water in the milk.  The soap is attracted to both the fat and the water in the milk.  When you add it to the milk, it immediately begins to grab those parts, which results in a lot of mixing and movement, which, thanks to the food coloring, you can see. 

The soap also breaks the water's surface tension, allowing all kinds of movement to occur.

 These pictures were taken using 1% milk - try it using whole milk, with more fat molecules for the soap to grab onto and see what happens. 

How Does That Work: Doing the Back Float

This is a simple activity, but its explanatin is a bit sophisticated.  Therefore it's a good candidate for older and/or more advanced students.  But, don't let that stop you from trying it with younger students - keep your explanations basic and you might be surprised at what they take away from it.

What you'll need:

Baby oil

Water

Water bottle

Index card

Sharpened pencil

Hole punch

What to do:

Prepare a bottle, filled about half way with water and the remaining way with baby oil. 

On one side of an index card, color with a pencil, getting as much graphite as you can onto the index card.

Use a hole punch to punch the index card.

Place the hole punches into the bottle of oil and water.

What you'll see:
The dark side of the holes will always face the oil and not the water.  You can shake it up and they'll always return to that position.

Why:
Graphite is a good conductor, which gives it a negative polarity.  Water also has polarity, and it repels the graphite, so the graphite side will face the oil.


You can also talk about things like density, immiscibility and the like with this activity.

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How Does That Work is a series of products and demonstrations that you can present to your students and challenge them to explain the science of how they work. Make sure you decide ahead of time what you'll accept as a valid explanation - can it be printed straight off the internet, written in the student's own words, or does the student need to be able to explain it to you conversationally? What will a valid explanation earn the student - a prize, extra credit, a feeling of goodness?

How Does That Work: Frustration Bottles

There are so many things you can talk about with this demonstration: solubility, density, immiscibility, etc.  It also makes a good How Does That Work demonstration. 

In short:

You have three bottles, each made of two layers, but in one bottle the layers are reversed.  The bottles are filled with water (on the bottom) and baby oil (on the top).  In two of the bottles, the water is colored with water soluble food dye (which will color water but not oil).  In the third bottle, the oil is colored with liquid candle dye (which will color oil, but not water).

In long:

You'll need:

3 (500mL) water bottles

750 mL baby oil

750 mL water

food coloring

liquid candle dye

Fill 2 of the bottles with 250 mL of water.  Fill the remaining bottle with 250 mL of baby oil.

Use the candle dye to color the baby oil (do this before coloring the water - the water and food coloring are much more forgiving and easier to dispose of should you need to start over).

Use the food coloring to color the water, attempting to match the oil color as best you can.  Keep track of what you used and repeat with the second water bottle.

Into the bottle with the oil, add 250 mL of water.

Into the two bottles with water, add 250 mL of baby oil to each.  Cap.  (You may wish to run some glue along the cap so they are more resistant to being opened).

Leave the bottles on your front table/desk and let the students explore.  They'll try to turn the "wrong" one upside down.  They may try to shake them and then watch them separate.

Should lead to some good discussions!

You can keep these forever - put them in a safe spot until you need them the next time!

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How Does That Work is a series of products and demonstrations that you can present to your students and challenge them to explain the science of how they work. Make sure you decide ahead of time what you'll accept as a valid explanation - can it be printed straight off the internet, written in the student's own words, or does the student need to be able to explain it to you conversationally? What will a valid explanation earn the student - a prize, extra credit, a feeling of goodness?

Water: Mystery Jars

On first glance, this looks like an encore performance of the classic air pressure demonstration, using a Mason jar instead of a cup...

But look what happens when you knock the index card out of the way this time...


WHAT??? The water's still in the jar??? HOW???

The secret:


A piece of screen (regular window screen, found at your hardware store, or from a broken screen you have at home) placed inside the jar band.

Air pressure held the index card in placed, as discussed previously. Once the card is gone, surface tension takes over. The water molecules join together to form a membrane, strong enough to hold the water in, in the screen openings.

If you tip the jar, you'll break the surface tension, and...


This demonstration leads to some great experiments...
-how large of a screen opening can you use before the openings are too large to hold the water
-will other materials (cloth, etc.) work in the same manner
-what if you use soapy water
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PS While you're carrying out the demonstration, don't let the students see the top of the jar and the screen.

PPS You might want to do this with two jars and two volunteers. Set it up so that everything looks the same, except that one of the jars has a piece of screen in it and the other does not. Knock the index cards out of the way at the same time and SURPRISE! One of the jars spills all of its water, the other does not. Now, get someone to explain what happened!

This post is a part of:

Water: Drops on a Penny

How many drops of water do you think a penny can hold? Make a hypothesis as test it out... you might be surprised.

When beginning a unit or lesson on water, I like to ask my students to give me as many words as they can think of to describe water. I make a list on the board and at the end, add one or my own: sticky. Students look at me like I've lost my mind, but once they start on this experiment, they start to understand my description - the water drops stick to one another. A great introduction to the properties of adhesion, cohesion, and surface tension.


Encourage students to make up their own experiments. For example, which side holds more, heads or tails?

After going through the activity once, you can mess with your students a bit - put a little liquid soap in their water supply, or rub a little soap on the penny. The soap interferes with the surface tension and the pennies can't hold nearly as much water.

Oceans: Earth Ball Catch

Beg, borrow, steal or buy an inflatable globe or other spherical representation of the Earth that can be tossed around the classroom.

Have students throw the globe to one another around the room. When a student catches the globe, he/she should look to see if his/her left thumb is on water or land. The student will call out "land" or "water" and the teacher (or another student) keeps a tally of land and water catches on the board.

At the end of the game, analyze the data and you should find that about 70% of the time, the student's thumb was on water. A great introduction to a study of oceans and water - emphasizing the large percentage of the Earth that is covered with water.