Water Wars

Use your knowledge of air and water—and a little skill—to win this game!

Water has a lot of interesting properties that we typically take for granted. This simple activity gives kids a chance to experiment with water’s properties of surface tension and cohesion. They will also experiment with color mixing and recognizing that once colors mix together, they cannot easily be separated. This is a fun game that you can pull out any time.

Preparation

Tear off or cut several pieces of wax paper, about the size of a piece of copy paper, at least two for every team of two students. Mix up small cups of red water and blue water (or yellow and blue) by adding several drops of food coloring to cups of tap water. Ideally, the water will be a nice bright color. You should have cups of red water for half of your children and cups of blue for the other half.

Resources

Figure 1

Suggested Materials

Wax paper
White copy paper
Drinking straws (1 per student)
Food coloring
Small cups, any size (1 per student)
Black permanent marker (1 or a few)

Optional Materials

Eyedroppers (1 per student)

Opening Discussion

Ask your students if they have ever seen drops of water anywhere before. What shape do the drops take? Are they always that shape or can they be different shapes? Tell them that they will be experimenting with drops of water, and then they will play a game using those water drops.

The Challenge

Discover how drops of water act and react and play a game using what you discover!

Doing the Activity

Divide students into teams of 2 for this activity. Distribute one piece of wax paper to each team, a piece of copy paper and a straw to each child. Ask students to take a cup of colored water as well, making sure that one team member has blue water and the other has red (or yellow) water.
Ask students to place the copy paper between them, place the wax paper on top of it, and then experiment together by placing small drops of water on the wax paper and gently blowing them around the paper using the straw. If you are using eyedroppers to create the drops, make sure each student has one. If you do not have eyedroppers, show students how they can create drops by putting the straw into the water, placing their finger over the top of the straw and then raising the straw out of the water. They can then lightly lift up their finger from the straw and quickly place it back on to release drops from the straw. This takes some practice, so encourage kids to experiment. Have teams play around with the drops on the wax paper, and as you move from team to team, ask them to observe what happens when drops come together. Can they blow drops apart? Can they put them back together? Can they separate a blue from a red drop after they have come together?

Let’s Talk About It

After 5-15 minutes, bring kids together to talk about what they have done so far. What happened when two different-colored drops came together? What about two drops of the same color? Could they use the straw to split a drop apart? Could they then put it back together? If two different-colored drops came together, what happened to the color? Could they then separate that drop back into a red drop and a blue drop? How did they make the drops (if using straws)? Are there any tips or tricks for playing well? NOTE: for younger children, you can stop the activity here, and allow them to experiment some more with the drops.

Build On What They Talked About

After a brief discussion, tell your students that you would like to teach them a game called “Water Wars” using the same materials. Each team of two players will face each other, with the piece of wax paper (you’ll need new paper for each team) between them, lengthwise. Have each team draw a line across the middle of the paper, and a line on each end, an inch from the end of the paper. The wax paper will look like Figure 1.

The rules for the game are:

One player has blue water, the other has red (or yellow).
Each player should place 15 “mines” (colored water drops) on their side of the paper, between the middle and end lines.
The object of the game is to drip a new drop on your side of the paper, then blow it from your side to the “safe zone” (the space between the end of the paper and the line one inch in) on your opponent’s side and to create a large drop by merging any of your drops that you get into the safe zone. Keep score on a separate piece of paper of every drop that each player gets into the safe zone.
If a player hits a “mine” on their opponent’s side, the drops will merge and turn purple (or green). That player’s turn is over. Each player gets 10 turns.

Other rules:

If a drop splits, the player must blow it back together before continuing.
If a player hits a “mine” on THEIR side, they must split the drop apart into two again (only by blowing on the drop with the straw) before continuing, or forfeit their turn.
If a player blows their drop off of the piece of wax paper, even after crossing into the safe zone, their turn is over and they collect no points.
If a “mine” leaks through the wax paper, players may replace that drop anywhere on the same side of the paper.

Have teams play a few times, then come together to talk about the game. Was it easy or difficult? Are there any rules they would change? See “Suggestions” below for different rules ideas and extensions to the activity.

Suggestions

There are many different ways that kids can play games with these materials. Some suggestions include:
The “mines” are the drops that players will blow over to their opponent’s side. If a mine has been mixed with another drop, you may still blow it from your side to your opponent’s.
Players create a large drop of clear water on their own side (made up of 15 drops), and add 15 “mines” protecting this large drop. Players try to move their colored drops into their opponent’s goal drop and turn it their color with as many drops as possible.
Once children have played this game, and possibly some of the variations, invite them to create their OWN rules, then come up with a name for this game. You could even have them design a “box” for the game and create a print or commercial advertisement for it.
Water molecules are attracted to each other. This “stickiness” causes them to pull together, which makes water drops the smallest shape they can be…round (actually, a sphere). The water molecules on the surface of the bead are ‘holding’ each other together, or creating surface tension. You can see this tension at work if you gently blow a drop…it will change shape, but stay together because of this stickiness.
Gravity will cause some flattening or (in falling drops, along with friction) distortion, but at rest a drop is generally round in shape. The larger the drop, the heavier it is, so the more it appears like it has a flat top.