Water Sprayer
		Materials: A cup of water Two straws

Procedure: Hold one straw vertically in the water and the other horizontally so that the ends are close together. By blowing air into the horizontal straw, the student causes water to get sucked up and spray out of the vertical straw. This usually takes a little moving around of the blowing straw.

Explanation: The air from your breath curves around the top of the vertical straw. The streamline curvature allows the flow to sustain a pressure difference between ambient and at the straw tip. The faster you blow, the lower the pressure and therefore the greater the force to pull the flow up the straw.