Science · Year 3

Active learning ideas

Deposition: Building New Landforms

Students learn best when they can see forces at work in real time, especially when those forces involve movement and change over time. Hands-on models let Year 3 learners observe how slowing water or wind drops sediments to build new landforms, making abstract ideas visible and memorable.

• ACARA Content Descriptions
• AC9S3U02

• 30–50 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Hundred Languages
• 45 min · Small Groups

Model Building: River Delta Formation

Fill a long tray with sand and soil, add water from a height to simulate a fast river, then slow it at the end with a shallow pool. Students add coloured sediments and observe where they deposit. Discuss how the slowdown at the mouth forms a fan-shaped delta.

Explain how a river delta is formed.

Facilitation Tip

During Model Building: River Delta Formation, place the tray on a slight incline so students see how the river slows as it meets still water, clearly showing sediment drop-off.

What to look for

On an index card, ask students to draw a simple diagram showing how a river delta forms. They should label the river, the ocean, and the deposited sediment. Include one sentence explaining why the sediment is dropped.

• Understand
• Apply
• Create
• Self-Awareness
• Self-Management
• Social Awareness

Activity 02

• Hundred Languages
• 30 min · Pairs

Wind Simulation: Sand Dune Creation

Use a fan and tray of dry sand to blow particles into piles. Vary fan speed and direction to form different dune shapes. Students measure pile heights and sketch changes over multiple trials.

Compare the formation of a sand dune to the formation of a beach.

Facilitation Tip

During Wind Simulation: Sand Dune Creation, run the fan at different heights to show how dune shape changes with wind speed and direction.

What to look for

Pose this question to small groups: 'Imagine you are observing a river. Where would you expect to find the most deposited sediment, near the fast-flowing rapids or in the wide, slow-moving pool downstream? Explain your reasoning, considering how water speed affects sediment transport.'

• Understand
• Apply
• Create
• Self-Awareness
• Self-Management
• Social Awareness

Activity 03

• Hundred Languages
• 50 min · Small Groups

Stream Table: Speed vs Deposition

Set up stream tables with adjustable flow rates using pumps. Pour sediment-laden water at fast and slow speeds, mark deposition zones, and compare results. Groups predict and verify outcomes.

Predict where sediment would be deposited in a slow-moving river versus a fast-moving river.

Facilitation Tip

During Stream Table: Speed vs Deposition, mark two flow rates on the table with tape so students can compare deposition at 5 cm/s and 20 cm/s.

What to look for

Show students images of a sand dune and a beach. Ask them to write down two ways their formation processes are similar and two ways they are different, focusing on the agent of deposition (wind vs. waves).

• Understand
• Apply
• Create
• Self-Awareness
• Self-Management
• Social Awareness

Activity 04

• Hundred Languages
• 35 min · Whole Class

Beach Wave Tank: Coastal Build-Up

In a wave tank, students generate waves with paddles over sand, observing how they sort and deposit finer particles on the shore. Record changes after 10 wave cycles.

Explain how a river delta is formed.

Facilitation Tip

During Beach Wave Tank: Coastal Build-Up, add a small paddle to create consistent waves and have students note how wave height affects sediment movement and build-up.

What to look for

On an index card, ask students to draw a simple diagram showing how a river delta forms. They should label the river, the ocean, and the deposited sediment. Include one sentence explaining why the sediment is dropped.

• Understand
• Apply
• Create
• Self-Awareness
• Self-Management
• Social Awareness

A few notes on teaching this unit

Experienced teachers know that misconceptions about “faster equals more deposition” persist until students test their own predictions with real data. Use quick trial-and-repeat cycles so students see how heavier particles settle first, then lighter ones as speed drops. Keep talk time short and model time long, focusing on evidence students gather from their own setups rather than explanations from the teacher.

By the end of the activities, students will be able to explain why slower speeds deposit sediment first, describe how wind and water shape dunes and beaches differently, and predict where deposition happens in slow versus fast rivers using evidence from their models.

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Watch Out for These Misconceptions

• During Stream Table: Speed vs Deposition, watch for students who predict the fastest flow will drop the most sediment.

  Have students predict deposition patterns at two marked flow rates, then run the table for 60 seconds at each speed. Ask them to compare where sediments settled and why heavier pieces drop first in slower water.

• During Wind Simulation: Sand Dune Creation, listen for comments that wind only moves sand in rivers.

  Run the fan first over a flat tray, then add a small mound of sand to show how wind slows and deposits sand into dunes. Ask students to trace the wind’s path with their fingers to see where air speed changes.

• During Model Building: River Delta Formation, expect claims that deltas form in one rainstorm.

  After the first pour, ask students to sketch the delta, then add three more slow pours over the same tray. Have them label how the delta grows gradually, reinforcing the idea of repeated deposition over time.

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Methods used in this brief

• Hundred Languages