Power of falling water | BCHydro Power Smart for Schools

Power of falling water

Watch how the power of falling water generates electricity.

Activity Image
15 mins


The water cycle is at the heart of clean and renewable electricity in B.C. Melting snow and falling rain powers the province with hydroelectricity. A quick video takes us along the path of electricity from a dam to your home. 

BC Hydro


What you'll need

  • “Power of falling water” worksheet
  • "Power of falling water" video
  • Projector and screen to show video

  1. Things that use electricity can usually be plugged in and turned on. Can students think of some examples?
    • Find something in the room that uses electricity.
    • Ask students where they think the electricity comes from.
  2. Play the “Power of falling water” video.
  3. Review how electricity is made in a hydroelectric dam and talk about how important the water cycle is for generating electricity in B.C.
    • Precipitation falls as rain or snow.
    • It travels to rivers as runoff.
    • Some of the runoff collects in reservoirs (or lakes) behind a dam.
    • The water travels down big pipes at the dam and spins a wheel called a turbine to make electricity.
    • The electricity travels along wires called power lines to our homes and buildings where we can plug things in and turn them on.
    • Meanwhile, after water passes through the hydroelectric dam, it continues down the river to lakes and oceans.
    • The sun causes water from rivers, lakes and oceans to evaporate and rise up into the sky.
    • The water droplets condense and form clouds.
    • Eventually, there are so many water droplets in the clouds that they get too heavy and fall back to earth as precipitation.
  4. On the “Power of falling water” worksheet, have students trace the path of electricity in red and the water cycle in blue.
    • What questions do students have about hydroelectricity or the water cycle?

Modify or extend this activity


  • Take students on a field trip to a BC Hydro facility. If there are no visitor centres in your area, check out these 360-degree images of Stave Falls Dam.
  • Go for a walk in your community to look for signs of the path of electricity - from the outlet to the meter to power lines and substations.

Curriculum Fit

Grade 2 Science 


  • Water sources including local watersheds
  • Water cycle

Curricular competencies

Questioning and predicting
  • Ask questions about familiar objects and events
  • Make simple predictions about familiar objects and events
Processing and analyzing data and information
  • Sort and classify data and information using drawings and pictographs
  • Communicate observations and ideas using oral or written language, drawing or role-play

Teaching Notes


The story of hydroelectricity starts in nature with the water cycle. Snow falls in winter where it collects in high-alpine glaciers and creates a dense, thick snowpack. In the spring, this snowpack melts and the run-off makes its way down the mountain and into streams and rivers. Water from the melting snow and ice, as well as rainwater, collects in reservoirs behind dams.

When water in a hydro reservoir is released it moves through large pipes, called penstocks, to turbines, which are like wheels with blades. The energy of falling water spins the turbines and generates electricity.

The electricity is transported to your home,  traveling long distances over high-voltage wires called transmission lines. These transmission lines are held above the ground by tall metal transmission towers.

When the electricity gets near a town or city, it goes into substations. A substation contains many wires and transformers and is surrounded by a fence. The substation reduces the voltage, divides the electricity and sends it in different paths over wires called distribution lines. These distribution lines take the electricity to your home and can be either above ground or underground.

When you see grey cylinders on power poles, they’re called transformers. They reduce the voltage on the distribution lines to an amount that can be safely used in buildings. You may also see metal boxes with warning signs where newer houses are built. These boxes are called pad-mounted transformers. They do the same things as the transformers on the poles, but are for underground distribution lines.

As the electricity enters your house or school, it passes through a meter. The meter measures the amount of electricity your household uses. The electricity flows through the meter, through wires in your house and ends in electrical outlets in the walls. To use the electricity, you plug the appliance or device into the outlet.

Water cycle

Earth has a limited supply of water that is cycled over and over again. The water cycle is an important process on earth because living things, including animals and humans, need water to grow and survive. Water is used for drinking, growing food, providing habitat, generating electricity and more. The sun has been driving the water cycle on Earth for billions of years. The four main stages of the water cycle are evaporation, condensation, precipitation and runoff.

  • Sun: The water cycle is driven by the energy from the sun warming the earth.
  • Evaporation: The warmth of the sun causes water from lakes, rivers and oceans to evaporate and turn from a liquid to a gas. The water vapour (gas) rises up into the air
  • Condensation: The water vapour cools as it rises and turns into water droplets, forming a cloud.
  • Precipitation: Water droplets in a cloud eventually become too big and heavy and fall from the clouds in the sky. It can fall as rain, snow, hail, etc.
  • Runoff: After the precipitation falls, it flows down towards the ocean and collects in rivers, lakes and streams. Some of it collects underground as well. 
  • And then the cycle begins again.


  • Assess the “Power of falling water” worksheet for student understanding of how hydroelectricity is related to the water cycle.
  • Assess student participation and communication skills while sharing ideas of what uses electricity, making predictions about where electricity comes from and generating questions.

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