Transporting Water and Finding Equilibrium

You may have seen images of this activity before... I know versions of it have been prevalent on Pinterest.  We'll go through the basics and then we'll talk a bit about stepping it up and stretching your kids' brains!

In its basic form, you begin with 3 cups, some water, food coloring and a paper towel.

Fill two of the cups with water and color the water in each cup a different color.

Arrange the cups in a line, with the empty cup between the cups with colored water.

Take a piece of paper towel (I used half a paper towel) and twist the middle a little.  Then bend the towel so that it creates a bridge from one cup to another.  Repeat with another paper towel to connect the other two cups.

Observe.


The water will move from each of the cups, through the paper towels into the empty cup.  You'll know water has moved because there is now water where before there was none and you'll know that it has come from both cups because the center cup will contain green water (the combination of yellow water and blue water).

The movement happens fairly quickly - the process will be complete within a couple of hours.  

It may not be terribly obvious, because we tend to start with about equal amounts of water in the two cups with which we start, but the water will keep moving until all three cups have equal amounts of water in them.  

At that point, water stops moving and system will basically just sit there.  The cups have reached equilibrium. You can let the cups sit there for days and you won't notice much changing. 

I took this photo before the system had reached equilibrium and forget to take another one after the process was complete.  But I can assure you that all three cups finished with an equal amount of water.

Now is when you can really challenge your students to figure out what's going on within the system.  What will happen if more water is added to the system?

You can add water by pouring more water into any one of the cups in the system.  Or you can add a fourth cup to the system and connect it with a paper towel.

I chose to add another cup of water (uncolored this time) and connect it to the middle (green) cup with a paper towel.

Make sure the cup you add to the system has a different water level than what's in the other cups or you won't get any movement.  I was trying to move water into the green cup, so I made sure my new cup was pretty full of water.  You could also connect an empty cup to the system via paper towel and watch the water flow in the other direction.

The system that had been sitting dormant for several days sprang into action. 

Colorless water flowed into the green cup (as evidenced by the lightening of the green color).  Green water then flowed into the blue and yellow cups (as evidenced by the color change in those cups). 

A really simple experiment with a lot of permeations - you can keep playing with it day after day, adding water or empty cups at different spots in the system.  Really great for inquiry learning and exploring!

How Many PIeces if Pasta in the Jar

Originally posted on February 1, 2010

Provide each group of students with two jars - one filled with tiny pasta and a second that's empty, as well as a variety of measuring tools: balances, rulers, graduated cylinders, etc. The group is to use the allotted time to determine the number of pieces of pasta in the jar.

I have used this at the beginning of the year and when forming new lab groups - a chance for the team to work together to find a solution. A good opportunity to observe students and their ways of thinking.

Zack's Alligator: Measurement and Graphing Exercises

Zack's Alligator is the story of a boy who is given a tiny alligator on a key chain, with the instructions to water her every day.  When given water, Zack's alligator grows and grows and they're off on all sorts of adventures. 

You can have your own adventures in science with a growing alligator.  (Of course you can use another other "Growing" animal, the alligator just complements the book nicely).

Before you place the alligator in any water, take some measurements.  The number and type of measurements you take will depend upon the age of your students.  Some possibilities:

• Length (nose to tail)
• Width - across the head
• Width - from toe to toe
• Thickness
• Mass
• Volume
• Density (not a measurement, but could be calculated if you have mass and volume data)

I did this with a very young student, for whom measurements are meaningless, so we traced around the alligator.   (FYI, I used the back side of a sheet of freezer paper - I could get a nice long sheet of paper, and it's plasticated, which was important since future tracings would be made when the alligator was wet).

After measuring, the alligator can be placed in a large tub of water (you want to make sure it has room to grow). 

Each day, for about a week, take each of the measurements.

At the end of the week, you'll have a collection of data.

Our data was a picture, showing the alligator's growth:

If you have numerical data, you can create graphs that illustrate the rate of growth.  You can then analyze whether the alligator grew faster in one dimension than another or if they all grow at the same pace. 

Denisty: Candy Density

This is really just another way to get your students to practice measuring and calculating density.  But, it involves the use of candy, so it's more interesting than your run-of-the-mill density calculation.

The original version of this activity uses Whoppers, Lemon Heads and jelly beans.  You could certainly modify that to use whatever you have available and/or is on sale.  However, you will want to make sure you have a variety of densities present in your candy selection.  The Whoppers are nice, because they will float.

You'll want students to use 3 pieces of each candy, so they can average their data.  (This could be done in groups, to save time and candy usage).

First have students find the mass of each piece of candy.  Then they'll find the volume via water displacement.  Because the Whopper floats, they'll need to use the tip of a pencil to push it down, so it's just below the water surface.  Finally, they can calculate the density.

If you wish to take it a step further....
After calculating the density of individual pieces of candy, have them calculate the density of all three pieces at the same time.  The mass and the volume will each be lager than they were for the individual pieces, but the density will remain the same (assuming all measurements and calculations are made accurately).  It's a good opportunity to remind students that density is an intensive property, not dependent upon the amount present.  And, by making it a hands-on reminder, your students are more likely to remember it!

Write It, Do It

Write It, Do It is a Science Olympiad event, but it can easily be adapted for use in your classroom. 

The idea is to get kids to practice writing clear technical directions. 

As a competition event, students work as a team - one member is the writer and the other is the do-er. 

The writer is given an object made of Legos, K'nex, Tinker Toys, craft supplies, etc.  The writer then has to write a set of instructions explaining how to build that object. 

The do-er is then given those instructions, along with a set of the materials needed to construct the object. 

The goal is to have a finished object that most closely resembles the original object. 

Science Olympiad has a thorough list of rules that govern the event - no drawings, all abbreviations must be defined, etc.  But, in your classroom, you can set your own rules.  For me, the goal is to get the kids to write accurately and provide clear directions. 

Start simple and work up to more complex objects throughout the year, as your students technical writing skills improve. 

If you plan to do this activity throughout the year, seek out a variety of different materials with which to build - it will make things more interesting and challenging if it isn't always the same.  Yard sales and thrift stores are great places to pick up building toys on the cheap - and you can sometimes find some older toys that your students don't know, adding to the challenge!  Just make sure you have at least 2 of each part - one for the object, one for the building materials. 

Make Your Own Play Doh

If you've been following this blog for awhile, you know there are several different activities in which Play Doh is a featured supply.  If you're beginning to find it expensive or inconvenient to have Play Doh on hand when you need it, you can make your own. 

It's so simple and quick, you can do it in the morning before you go to school!

You'll need:

• 1 cup flour
• 1/2 cup salt
• 1-2 tablespoons cream of tarter*
• 1 cup water
• 1 tablespoon cooking oil
• food coloring

*cream of tarter is found in the spice section of the grocery store.  Without it, your Play Doh will not set up properly - it will remain a gloppy mess. 

In a medium-sized saucepan, combine the flour, salt and cream of tarter.

If desired, add the food coloring to the water.  This is the less-messy way to color the play-doh, but your batch will all be one color.  If you want to split it into multiple colors, you can wait and knead in the coloring at the end.

Place the pan over medium heat and stir in the (colored) water and oil.

Stir the mixture constantly.  When the mixture forms a ball around your spoon, remove it from the heat. 

Remove the play-doh from the pan and knead it slightly.  This is the point at which you could divide it and add coloring to each portion. 

When you're finished, you'll have a nice sized lump of play-doh.  It's probably equivalent to about 3 of the large containers of Play-Doh.  (That's a guess, it might actually be more than that). 

Here are some of the things you can do with your newly-made Play Doh:
Mixing Colors: The Play Doh Version
What's Inside?
Mapping: Make a Topographic Map
Moon vs. Earth: Volume Comparison
Plate Tectonics: A Look Inside Folds and Faults

Weather: How Much Air is Pushing on You?

The air all around you is filled with molecules, all of which exert pressure on you. 

Picture this...
You're standing upright.  Rising straight up from your head, into the furthest reaches of the atmosphere, is a column.  This column is filled with air molecules.  While the effect of each individual molecule is miniscule, their combined effect is a force with which to be reckoned.  How much atmospheric weight do you think your head has to support?  Go ahead, take a guess...

First we need to find out how large your head is.  For the purposes of this activity, we're going use inches so we can get an answer in pounds.  It's rather un-scientific of us, but it will provide us (in the U.S.) with the greatest understanding.

Back to your head.... find the circumference of your head, using either a fabric measuring tape or a length of string that you then lay against a meter stick.  I come up with 22 inches.

Now you'll need to do some math to find the radius.  Circumference is equal to 2 x pi x radius.  So, to get the radius, you'll need to divide the circumference by pi and then divide that number by 2.  For me, it's 3.5 inches.

Now you'll use the radius to find the area of the top of your head.  Area is equal to pi x radius x radius.  For me it's 38.47 square inches. 

Atmospheric pressure at sea level is 14.7 psi (that's pounds per square inch), and while I don't live exactly at sea level, that number will work well enough for our purposes.  So, the area of my head multiplied by atmospheric pressure gives me the weight of air pushing on my head.  In my case, it's 38.47 square inches x 14.7 psi = 565 pounds. 

Pretty unbelievable, isn't it?  But it's true.  We aren't aware of it because we're used to it, we've never known anything different.  And we aren't crushed by that force because there are fluids inside our body exerting pressure that keeps things balanced.  Those air molecules are pushing on all sides of your body, not just on top of your head, which also helps keep things balanced.

If you're interested, atmospheric pressure in Denver, with an approximate altitude of 1 mile, is 12.2 psi.  You might want to have your students determine how much the atmospheric weight changes as they go from sea level to 1 mile.

Density: The Sugar Density Column

Did you know that you can change the density of water by adding sugar to it?  Did you know that you can actually create layers of sugar water that have different densities? 

I've seen the Flinn Version, How Sweet It Is, numerous times, and it's very cool. Unfortunately, it's not very practical for me.  I'm not in a classroom, so I don't have balances readily available, nor do I have access to ring stands and separatory funnels.  I've always figured I could find a way to recreate the experiment to make it work for me, but I've just never made it that far down my list of things to do.

And then I found this version, which does not require any of the aforementioned equipment.  (I have adapted it slightly to include two additional colors).  And, if you're just planning to make the solutions ahead for demonstration purposes, it's faster.  In fact it's perfect for doing at home.  It's also simple enough for young students to help with. 

Now, before I go on to show you how simple it is, let me point out that for older students the Flinn version may be superior:
1 - It's always good to practice using equipment to make accurate measurements.
2 - In the Flinn version, students find the mass of the sugar, which allows them to calculate the actual density of each solution.  You could also have them calculate the sugar concentrations.

Enough talking, on with the fun!

Line up 5 glasses.  Add sugar to the glasses as follows:

Glass 1: no sugar
Glass 2: 1 tablespoon
Glass 3: 2 tablespoons
Glass 4: 3 tablespoons
Glass 5: 4 tablespoons
Glass 6: 5 tablespoons

Add 4 tablespoons of water to each glass and stir to dissolve the sugar.  Make sure the sugar in each glass is completely dissolved.  If you need to add water to one glass, you'll need to add an equal amount of water to each of the other glasses.

Add food coloring to the glasses, a total of 2-3 drops per glass, as follows:

Glass 1: red
Glass 2: red + yellow
Glass 3: yellow
Glass 4: green
Glass 5: blue
Glass 6: blue + red

To make the column:

Pour the purple solution into a tall, colorless glass (or a graduated cylinder if you have one). 

Hold a spoon over the glass, near the top of the purple solution, and pour the blue solution slowly over the back of the spoon.  This technique will minimize the mixing of solutions.

Using the same technique, add the remaining solutions in the following order: green, yellow, orange and red.

As you can see, I haven't yet perfected the pouring technique, but it isn't completely muddled either.  I think I could have gotten a better rainbow if I had tried again immediately after doing this one, but I decided it wasn't worth using a bunch more sugar just to capture a better photo.  That said, I think my rainbow looked better than the above photo shows - I just couldn't get the light right to show all the colors. 

If you're doing this as a demonstration, you very well may want to make sure you have enough solutions to give yourself a test run before the actual assembly.

Observation: Sounds in a Quiet Room

So often, when speak of observation skills, we focus only on sight and neglect the remaining 4 senses.  Put your students ears to work with this exercise. 

Students will sit quietly for 5 minutes, just listening and writing down the sounds they hear.  It's amazing how much noise there is, even when things are quiet!

Any students who make intentional noises will have their grade docked accordingly. 

This is also a great activity to do outside on a nice spring (or fall) day.

Earth Day: The Lorax

The Lorax is a great story to share with your students around Earth Day (or any other time, for that matter).

There is a video available, but I'm partial to reading to my students (and they seem to enjoy it as well). 

Following the telling of the tale (or the watching of the DVD), have your students consider the following:

• What does a "Thneed" represent?
• List some "Thneeds" in our society today.
• Who does the "Once-ler" represent?
• How was the "Once-ler" irresponsible?
• What could the "Once-ler" have done to protect the natural resources while still manufacturing "Thneeds"?
• Did the "Once-ler" feel that he was part of the Truffula Land?  Explain.
• Can we separate ourselves from our natural environment?  Why or why not?
• The "Once-ler" excuses himself with "Well if I didn't do it, then someone else would."*  Is this a valid excuse?  Why or why not?
• Who does the "Lorax" represent?

*In the video version (at least in an older version, it looks like there's a newer edition, which I haven't seen, so I don't know if it's word-for-word the same or not). 

What's Inside?

Here's another "black box" experiment to help your students understand what it means to be a scientist. 

Insert a small object into a ball of play dough or clay.  Make sure the object is surrounded completely.  Some ideas for objects to use: small screw, nut, button, marble, coin, pencil-top eraser.

Provide students with the play dough ball and an unfolded paperclip. 

The student uses the paperclip as a probe.  He can stick the probe into the play dough ball, without wiggling it around, 10 times.  The student then draws a picture of what he thinks the object looks like and hypothesize what the object is.

Website: cK-12 Flexbooks

cK-12.org is a website that contains free digital textbooks for science and math courses.  You can use the textbooks as is, or you can customize the books to your liking, incorporating text and pictures from various sources into one book.  The resultant book can be used as an ebook, or it can be made into a pdf document, which could be printed or shared as you would any pdf file.  The books are all open source, so you shouldn't run into copyright issues.  You can read more about the policies in the Frequently Asked Questions. 

In full disclosure, I have not spent a lot of time playing with the flexbooks, as I don't currently have need for a textbook.  But, I thought it a worthy resource to pass along for teachers looking to supplement their current texts and parents looking for resources for their students, especially in an economic climate where new textbooks may drop a step or to on the priority list. 

If you create your own flexbook (or have already done so), I'd love to hear about your experience and how valuable a tool you found this to be.  

Public Service Announcement: Dihydrogen Monoxide: UPDATE!

April Fools*!!

Dihydrogen monoxide is another name for water - dihydrogen means 2 hydrogen atoms and monoxide means 1 oxygen atom - H2O!

Share the information from the Coalition to Ban Dihydrogen Monoxide with your students and see if you can get them going - some of them will jump right on board!  (You probably work with some people who would join the crusade as well)

It's another lesson in making sure you think and evaluate as you read and listen - everything stated in the "article" is true, but I don't think anyone really wants to ban water. 

I've also used this activity with students learning about the rules of compound nomenclature and it has the same effect, whether it's April Fool's Day or not.


*Yes, I know April Fool's Day isn't until tomorrow, but if I waited until tomorrow to share this gem, you would have to wait a whole year before sharing with your students and that just didn't seem right.

Measurement: The Symmetrical Human Body

Practice measuring length while learning a little more about your body.

The human body is proportioned with almost exact symmetry.  This symmetry allows a ballerina to leap gracefully, an athlete to run fluidly and a child to stop suddenly.  It also gives each of us the balance we need for our organs to function healthfully.

The human body's proportions are often expressed in terms of the length of your head.  Measure the following lengths and see how closely your body fits the mold. (These measurements are for adults, your students might not fit them yet as proportions change as we grow into adulthood).

Record all measurements in cm.

Measure the length of your head. ____ cm

The height of an adult is 8 times the length of the head, or 8 "heads".  Your height is ____ cm, which is ____ heads.

The distance from your hips to your feet is 4 heads.  This distance on you is ____ cm or ____heads.

The length of your head should equal the width of your waist.  Does it?

Your knees are 6 heads from the top of your head.  This length on you is ____ cm or ____ heads.

The width across the shoulders is 2 heads.  Your shoulder width is ____ cm or ____ heads.

The length of your foot equals 1 head.  Your foot length is ____ cm or ____ heads.

The length of your forearm from the inside crease of your elbow to the wrist bone equals 1 head.  This length on you is ____ cm or ____ heads.

Your waist is 3 heads down from the top of your head.  This length on you is ____ cm or ____ heads.

Your hands reach the middle of the thigh, or 5 heads down.  This distance on you is ____ cm or ____ heads.


**See what other proportions you can come up with.  For example:
--Your forearm is the same length as your foot.
--The length of your pinkie is the height of your ear.

Fossils: Digging for Dinosaur Bones

Keep your eyes out for puzzles similar to these (I've found them at Michael's, for only a buck or two each):

They're wooden sheets of pieces that you punch out and then assemble.  The paper inside the package tells you how to assemble the pieces, but you don't need it for this activity. 

Punch out the pieces for one dinosaur and bury the pieces in a bucket of sand.  Have students dig out the pieces and then try to assemble the pieces.  Without the instructions in front of them, they'll be working as paleontologists do, trying to determine how the bones go together. 

Some other ideas to consider:
*Mix up pieces from two different dinosaurs in the same bucket of sand - students have to determine which bones go with which fossil, as well as assembling them.
*Don't put all of the pieces in the bucket - you don't always find a complete skeleton in one place.
*Consider putting the pieces in something that requires more excavation than just pulling the pieces out of sand. 

Even if your curriculum doesn't include a study of dinosaurs and/or fossils, you can use this activity as a lesson on the way scientists work.