Science · Grade 6 · Environmental Systems and Stewardship · Term 4

The Water Cycle and Watersheds

Students investigate the components of the water cycle and how water moves through local watersheds.

• Ontario Curriculum Expectations
• MS-ESS2-4

About This Topic

Watersheds and Water Quality introduces students to the concept that everyone lives 'downstream' from someone else. They study how water moves through the landscape, from high points to low points, forming watersheds. In Ontario, this is vital as we are stewards of the Great Lakes, which hold 20% of the world's fresh surface water. Students learn how land use, such as farming, industry, and urban development, affects the health of these water systems.

This topic emphasizes the importance of wetlands as natural filters and the role of Conservation Authorities in Ontario. Students also learn about Indigenous perspectives on water as a sacred living entity and the role of 'Water Walkers' like Josephine Mandamin. This topic comes alive when students can model a watershed and observe how pollutants spread through a system in real-time.

Key Questions

1. Explain how water moves through the local landscape as part of the water cycle.
2. Analyze the interconnectedness of different parts of a watershed.
3. Predict the impact of urbanization on the natural flow of water in a watershed.

Learning Objectives

• Explain how water moves through the local landscape as part of the water cycle, identifying key stages like evaporation, condensation, precipitation, and runoff.
• Analyze the interconnectedness of different parts of a watershed by tracing the path of water from higher elevations to a common outlet.
• Predict the impact of urbanization on the natural flow of water in a watershed, considering factors like increased impervious surfaces and altered drainage patterns.
• Classify different types of water bodies (rivers, lakes, wetlands) within a watershed and describe their roles in the water cycle.
• Evaluate the effectiveness of natural and engineered solutions for managing stormwater runoff in urban watersheds.

Before You Start

The Water Cycle

Why: Students need a foundational understanding of evaporation, condensation, and precipitation to then analyze how these processes occur within a specific landscape.

Properties of Water

Why: Understanding that water exists in different states and can change states is crucial for grasping the movement and transformations within the water cycle.

Key Vocabulary

Watershed	An area of land where all the water that falls on it drains off and collects in a single common outlet, such as a river, lake, or ocean.
Runoff	The flow of water over the land surface, occurring when precipitation exceeds the rate at which water can infiltrate the soil or be stored.
Infiltration	The process by which water on the ground surface enters the soil, moving downward through pores and cracks.
Impervious Surface	A surface that does not allow water to pass through it, such as pavement, rooftops, and compacted soil, which can increase runoff.
Groundwater	Water held underground in the soil or in pores and crevices in rock, which can be replenished by infiltration.

Watch Out for These Misconceptions

Common Misconception

Water pollution only comes from big factories (point source).

What to Teach Instead

Explain that most pollution today is 'non-point source,' like oil from driveways or fertilizer from lawns. The 'Crumpled Paper' activity is excellent for showing how small amounts of waste from many locations combine into a major problem.

Common Misconception

A watershed is only the water (rivers and lakes) itself.

What to Teach Instead

Clarify that a watershed includes all the land that drains into a body of water. Using a topographic map of their local area helps students see that their own backyard is part of a larger watershed system.

Active Learning Ideas

Inquiry Circle: Crumpled Paper Watershed

Students crumple a large sheet of paper, then slightly uncrumple it to create 'mountains' and 'valleys.' They use markers to draw 'pollution' on the peaks and spray water to see where the 'runoff' collects.

40 min·Small Groups

Stations Rotation: Water Quality Testing

Students test different water samples (tap, pond, 'simulated' runoff) for pH, turbidity, and temperature. They must determine which sample is healthiest for local fish species.

60 min·Small Groups

Think-Pair-Share: The Sacred Water

Students read about the Indigenous-led Water Walks around the Great Lakes. They discuss in pairs how viewing water as a 'relative' rather than a 'resource' might change how we treat our local rivers.

20 min·Pairs

Real-World Connections

• Conservation Authority staff in Ontario regularly monitor water levels and quality in local watersheds, using this data to inform flood control measures and protect natural habitats. They might use stream gauges to track flow rates after heavy rainfall.
• Urban planners and civil engineers design stormwater management systems, such as retention ponds and permeable pavements, to mitigate the effects of increased runoff from developed areas, aiming to reduce flooding and water pollution.
• Farmers utilize knowledge of their local watershed to manage irrigation and prevent soil erosion, understanding how land use practices upstream can affect water availability and quality downstream for their crops and livestock.

Assessment Ideas

Quick Check

Provide students with a simplified map of a local watershed. Ask them to draw arrows showing the direction of water flow from various points to the main river or lake. Then, ask them to label one area that might experience increased runoff due to urbanization.

Discussion Prompt

Pose the question: 'Imagine a new shopping mall is built in our watershed. What are two ways this development could change how water moves through our local landscape, and what might be the consequences?' Facilitate a class discussion where students share their predictions.

Exit Ticket

On an index card, have students define 'watershed' in their own words and then list two human activities that can impact the health of a watershed. Collect these to gauge understanding of core concepts.

Frequently Asked Questions

What is a watershed?

A watershed is an area of land where all the water that falls on it drains into a common outlet, such as a river, lake, or ocean. Think of it like a giant basin where every drop of rain eventually flows to the same place.

How can active learning help students understand water quality?

Water quality is often invisible. Active learning through chemical testing and physical modeling makes the invisible visible. When students see 'pollutant' dye travel from a model farm into a model lake, they understand the connection between land and water far better than they would by just looking at a diagram of the water cycle.

Why are wetlands important for water quality?

Wetlands act like 'nature's kidneys.' They slow down water, allowing sediment to settle, and the plants and microbes in the wetland actually break down or absorb many harmful pollutants before the water reaches larger lakes.

What are the main threats to Ontario's water?

Key threats include urban runoff (salt and oil), agricultural runoff (fertilizers), and invasive species. In some communities, access to clean drinking water remains a critical issue, particularly on some First Nations reserves.