Sustainability New

Build a watershed

Build a working model of a watershed and see how water is collected and moves through a dam to generate electricity.

Activity Image
30 mins
Hands on


After discussing how dams are used to hold water in reservoirs and generate electricity, students will build their own model of a watershed using modeling clay, including a dam, and see how water moves at different stages of construction.


What you'll need

  • Digital projector and screen
  • “Make a watershed” instruction slideshow (to share with students or use as a teacher instruction only)

Materials for watershed model

  • 1 tray or other container per group of 2-3 students (about 20cm x 20cm x 1cm minimum deep) 
  • Block of modeling clay for each group of 2-3 students, plus smaller block (1/4 size) of a different colour for each group. 
  • 1 pack of toothpicks
  • 1 jug with water


  1. Before starting this activity, complete activities “Natural versus human-made” and “A water to electricity story” to learn about natural and human-made features in B.C. and how we make electricity.
  2. Have students share examples of natural features like water, trees, rivers, and human-made features like clothes, games, and buildings. 
  3. Consider that in B.C. we have natural features like mountains and water which combine with human-made features like dams to make electricity to power our lights and TVs.
  4. Discuss that a dam's like a wall, and it holds large amounts of water in one place forming a lake which we call a reservoir, and water's used to generate electricity.
  5. Explain that to make electricity the water in the lake drops from very high up and flows down pipes called penstocks. The speeding water spins a wheel called a turbine, making electricity. The electricity travels through wires to our homes and powers our lights and TVs. 

Make a watershed 

  1. Pull up the “Make a watershed” instruction slideshow if you want to share step-by-step images.
  2. Get students to form small groups of 2 to 3. Each group will work together to create a watershed model.
  3. Provide each group with a tray or container and one block of a single colour clay for each student.  
  4. Ask students to divide their clay in half and make 2 mountains, creating 4-6 mountains total for the group.
    • Step 1: Have students place their mountains on the tray in a circle leaving a gap about the length of one finger.
    • Step 2: Hand out another small amount of the same colour clay to each student. Ask students to join their mountains together forming a tight seal mountain to mountain and onto the tray.  When all groups have made their circle of mountains, ask what they think will happen if it rained down on the mountains? Students can predict the rain would run down the mountain side and out the gap between the mountains. 
    • Step 3: Test out the prediction by pouring a small amount of water on the mountains of each model.
    • Step 4: Hand out a smaller block of a different colour clay to each group and ask them to close the gap between the mountains by creating a wall called a dam. Ask students what they think will happen if it rained down on the mountains now? Some may predict the rain will run down the mountains and form a lake or reservoir. 
    • Step 5: Test out the prediction by pouring a small amount of water onto the mountains. Water should form a lake in the closed circle of mountains and dam. Prevent water spilling under the mountains by pressing the clay down firmly to the tray surface. 
    • Step 6: To create electricity, water travels down pipes called penstocks from the top of the dam to the bottom. Using a toothpick poke 2 to 3 holes on a downward slope from the inside of the dam to the outside. Use the toothpick to enlarge the holes to about twice the size of the toothpick. Students may need help for this step. Ask students what they think will happen if it rained down on the mountains now? Some may predict the rain will run down the mountains, fill up the lake or reservoir and run down the holes in the dam.  
    • Step 7: Test out the prediction by pouring water onto the mountains, and watching the lake fill up and water running out of the holes in the dam.
  5. On slide 9 to 12, share how this makes electricity. Water flows down the holes in our model which are pipes we call penstocks. The water moves very fast, turning a giant wheel called a turbine, making electricity. The electricity travels along wires to reach our homes to power our lights at home.

Modify or extend this activity

Curriculum Fit

Grade 1 Social Studies


  • Natural and human made features of the local environment 
  • Natural features: mountains, forests, waterways, local plants and animals
  • Human-made features: buildings, bridges, dams, dykes

Curricular competencies

  • Use Social Studies inquiry processes and skills to ask questions; gather, interpret, and analyze ideas; and communicate findings and decisions
  • Explain the significance of personal or local events, objects, people, or places

Grade 1 Arts Education 

Big Idea

  • Engagement in the arts creates opportunities for inquiry through purposeful play.

Curricular competencies

Exploring and creating

Create artistic works collaboratively and as an individual, using ideas inspired by imagination, inquiry, experimentation, and purposeful play.

Teaching Notes

Hydro electric generation system 

More than 90% of BC Hydro's generation is produced by hydro electric generation, which is generally the most cost-effective, clean and reliable option. BC Hydro also continues to investigate alternative sources of energy, such as wind and wave power.

BC Hydro generates over 43,000 gigawatt hours of electricity annually to supply more than 1.9 million residential, commercial, and industrial customers.

Over 80% of BC Hydro's installed generating capacity is at hydroelectric installations in the Peace and Columbia river basins.

How power is generated

BC Hydro generates power by harnessing the power of moving or falling water to produce mechanical/electrical energy. This power is delivered using an interconnected system of over 73,000 kilometres of transmission and distribution lines.

The power is generated as follows:

  • Hydroelectric dam: There is potential energy stored in a water reservoir behind a dam. It's converted to kinetic energy when the water starts flowing down the penstock, from the dam. This kinetic energy's used to turn a turbine.
  • Generator: The falling water strikes a series of blades attached around a shaft which converts kinetic energy to mechanical energy and causes the turbine to rotate. The shaft is attached to a generator, so that when the turbine turns, the generator is driven. The generator converts the turbine's mechanical energy into electric energy.
  • Transmission and distribution system: Transmission lines carry the electricity efficiently over long distances to power our lives.

For more information, read How power is generated.

BC Hydro’s facilities

 Explore dams in the Columbia Region, Peace Region, Vancouver Island and Lower Mainland: Find your dam.


  • Assess students’ ability to listen and follow instructions on how to build their watershed and dam.
  • Assess students’ participation and cooperation working in groups to build their models. 
  • Assess students’ basic understanding of how water moves through dams to make electricity.

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