The first thing to do is to get the class to split itself into groups and discuss as many different examples of the strength of water that they can. After they have brainstormed with their classmates they can make their presentations to the class. Topics such as the destructive nature of tsunamis and the electricity creating ability of the strength of water from hydroelectric power stations, wave power and ocean currents should be discussed.
To make their own water-powered generators, children will need a cheap electrical motor connected to a light bulb, a propeller and a wooden handle. The propeller should be attached to the bottom of the motor which, in turn, is connected to the wooden handle. Children should then place the propeller into a moving stream of water and watch what happens. The moving propeller should power the motor which should light the bulb. This is the same way that electricity is produced in a hydro-electric power plant, as flowing water turns the turbines which generate electricity.
For this exercise children will need a half gallon milk carton, a nail punch, some tape and some water. After cutting off the top of the milk carton, single holes of the same size should be made with the nail punch half and inch, an inch, two inches and four inches from the bottom of the side of the carton. A piece of long tape should then be placed over all the holes and the carton should be filled with water. Once this is done the tape should be removed and the results recorded. The jets of water at the bottom of the carton should land further from those higher up the carton. This is due to the weight of the water being greatest at the bottom of the carton. This follows the same principle as hydroelectric power stations, which generate electricity at the base of dams where the water pressure is greatest.
Get the class together to discuss tsunamis including what they are, how they are formed, where they occur and the after effects. The students should be aware of the power of tsunamis and know the signs to look out for if one is approaching. Use case studies of two tsunamis to illustrate the point, such as the 2004 Thailand tsunami and the 2011 Japanese tsunami looking at video footage of the events.