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!

Little Blue and Little Yellow: Color Mixing

Leo Lionni's Little Blue and Little Yellow makes an excellent addition to your study of colors and color mixing. 

Try it with one of these two activities that provide a mess-free hands-on way to mix colors.  If using these activities in conjunction with the story, you'll want to use the appropriate colors.  Or, you could have other colors and have your students write and illustrate their own versions of the story, using the colors they chose. 

Play-Doh Version
Start with two colors of Play Doh .  Use a small amount of each color.

 Knead the two colors together....

 You'll see the colors swirl together at first, and then combine to form a new color:

Here it is next to a sample of the original colors, so you can see what happened. 

You could have a lot of fun creating a Play Doh color wheel, or varying the amount of each color you used to create a whole range of shades.


Colored-Water Version

 Using the same technique used when learning to use a pipette, students can investigate mixing colors in a very simple, non-messy way.

Provide students with a pipette, wax paper, paper towel and  3 small cups - one with blue water, one with red water and one with yellow water.  Food coloring can be used to color the water (a small amount will go a long way), but food coloring does have the potential to stain, should the water spill.  Another option is to use the True Color Tablets available from Steve Spangler Science, which do not stain.

Students use the pipette to place drops of colored water on the wax paper.  They can then drag the different colored drops together and watch the colors mix. 

Challenge your students to make the entire color wheel.  Or see how many different shades of green they can create by mixing varying amounts of blue and yellow water.  Most importantly, allow them time to explore on their own to see what they can learn.

Mixing Colors: The Play Doh Version

Did you know you can use Play Doh to teach students about mixing colors?  A very tactile experience!

Start with two colors of Play Doh (I'd recommend beginning with primary colors, you can expand from there).  Use a small amount of each color.

 Knead the two colors together....

 You'll see the colors swirl together at first, and then combine to form a new color:

Here it is next to a sample of the original colors, so you can see what happened. 

You could have a lot of fun creating a Play Doh color wheel, or varying the amount of each color you used to create a whole range of shades. 

Mixing Colors

 Using the same technique used when learning to use a pipette, students can investigate mixing colors in a very simple, non-messy way.

Provide students with a pipette, wax paper, paper towel and  3 small cups - one with blue water, one with red water and one with yellow water.  Food coloring can be used to color the water (a small amount will go a long way), but food coloring does have the potential to stain, should the water spill.  Another option is to use the True Color Tablets available from Steve Spangler Science, which do not stain.

Students use the pipette to place drops of colored water on the wax paper.  They can then drag the different colored drops together and watch the colors mix. 

Challenge your students to make the entire color wheel.  Or see how many different shades of green they can create by mixing varying amounts of blue and yellow water.  Most importantly, allow them time to explore on their own to see what they can learn.