Fractions, Decimals, and Parts of a Whole · Term 2

Understanding Equivalent Fractions

Students use visual models (fraction bars, number lines) to understand why different fractions can represent the same amount.

About This Topic

Weathering and erosion are the twin processes that shape the Earth's surface over time. In this unit, students distinguish between the breaking down of rocks (weathering) and the movement of those materials (erosion). The Ontario curriculum emphasizes how these processes affect the local landscape, from the rugged Canadian Shield to the eroding bluffs of Lake Ontario. Students will investigate the roles of water, ice, wind, and living things in these changes.

This topic also introduces the concept of 'deep time' and how small changes can lead to massive geographical features like the Niagara Falls. Understanding erosion is also critical for discussing human impacts on the environment, such as how deforestation leads to soil loss. Students grasp this concept faster through structured discussion and peer explanation of their erosion models.

Active Learning Ideas

Inquiry Circle: Sugar Cube Weathering

Students shake sugar cubes in a container to simulate physical weathering and drop water on them to simulate chemical weathering. They compare the results and discuss which process was faster and why.

⏱ 30 min·Small Groups

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Simulation Game: The Erosion Stream Table

Using a tray of sand and a gentle flow of water, students observe how a river carves a path. They then add 'trees' (twigs) or 'houses' (blocks) to see how vegetation or human structures change the rate of erosion.

⏱ 50 min·Small Groups

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Gallery Walk: Ontario Landforms

Students look at photos of famous Ontario sites (Niagara Falls, Cheltenham Badlands, Flowerpot Island). They must identify whether weathering or erosion was the primary force at work and explain their reasoning on a shared chart.

⏱ 30 min·Whole Class

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Watch Out for These Misconceptions

Common Misconception

Weathering and erosion are the same thing.

What to Teach Instead

Weathering is the 'breaking' and erosion is the 'taking.' Using a 'break it and move it' mnemonic during hands-on activities helps students keep the two processes distinct.

Common Misconception

Erosion only happens during big storms.

What to Teach Instead

Erosion is a constant, often slow process. Time-lapse videos combined with classroom models help students see that even a tiny drip of water causes change over time.

Frequently Asked Questions

What are the best hands-on strategies for teaching weathering and erosion?

Stream tables are the gold standard for erosion, as they allow students to manipulate variables like slope and water speed. For weathering, 'freeze-thaw' experiments using plaster of Paris and water in a freezer can show how ice breaks rock, which is very relevant to the Canadian climate.

How does the Niagara Escarpment show erosion?

The soft shale at the bottom of the falls erodes faster than the hard limestone on top, causing the top layer to eventually collapse. This process has moved the falls several kilometers back from their original position.

How do plants help prevent erosion?

Roots act like a net that holds the soil together, and leaves break the fall of raindrops so they don't hit the ground with as much force.

Why is soil erosion a problem for farmers in Ontario?

The top layer of soil contains the most nutrients for crops. If it erodes away due to wind or water, the land becomes less fertile and harder to farm.

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