We've done one experiment on water pressure using a milk carton. This time we're going to use three cartons to make a higher column of water and see if we can get stronger pressure.

The top has been taken off one carton, and the other cartons have had both their tops and their bottoms removed. They are taped together, with the carton with the bottom, on the bottom. If you remember, we made three holes in the cartons we used before. We've done the same thing now, but all the holes are in the bottom carton. The holes are covered with tape, as before. Your teacher will turn a bucket upside down, and the cartons will stand on the bucket, with the side of the cartons that have the holes close to the edge of the bucket. You're going to be able to see the streams really well.

One student can hold a ruler so that one end of it touches the side of the carton next to the top hole. When the tape is pulled away, watch how far out the water goes before it falls to the ground, and notice which inch-mark it reaches before it falls.

We still have a carton left from the other project, and we'll measure the difference, by filling it, removing the tape, and noting the inch-mark the water reaches before falling to the ground. It didn't go as far as the water in the triple- decker did, did it? Let's try it with one bottomless carton taped on top of it, and measure the trajectory like we did with the triple-decker and the single carton. We can see that the water pressure from the double-decker carton is more than from the single carton, and the water pressure from the triple-decker is a lot more than from the double-decker.

Now, we'll do the triple-decker again but this time, we'll take the tape off the middle hole and compare it to the measurement we made when we pulled the tape off the top hole. After replacing the middle tape and filling the carton-stack again, we will pull the tape off the bottom hole. Wowie- Zowie! It really comes out of there, doesn't it?

It appears as though the higher the column of water, the harder the water pressure is. And, that the amount of water on top of the flowing water makes the pressure of the flowing water harder. It is the pressure that makes the water flow out to the side before it falls to the ground.