Year 5 · Autumn 1.1 · Step 6

Earth & Space

Plan — water resistance

Planning a comparative test: does the shape of an object change how quickly it sinks through water?

Arrival Starter I do We do Independent Exit ticket

🌱 Seedling · Working towards 🌿 Sapling · Expected 🌳 Oak · Greater depth

⏱ Whole lesson ≈ 44 min · pick a tier in the bar, or leave on "All"

Arrival 4 min

Recap of last lesson: evaluating the parachute test.

Recap: air resistance & fair tests

🌱 Seedling

Working towards

Air resistance is a type of ____.

🌿 Sapling

Expected

Name the three types of variable.
What did surface area do to the fall time?

🌳 Oak

Greater depth

Air resistance acts in air. What do you think happens to an object moving through water?

Bridge into todayAir isn't the only thing that resists movement. Today we meet water resistance and plan a test.

Starter 5 min

Think of moving your hand through water vs air.

Moving through water

Water resistance is a type of friction that acts on an object moving through water. Streamlined shapes meet less water resistance.

🌱 Seedling

Working towards

Which is streamlined?

a brick · a dolphin

🌿 Sapling

Expected

What does "streamlined" mean? Give an animal example.

🌳 Oak

Greater depth

Predict which shape will sink through water fastest, and say why.

I do · 1 6 min

Teacher models. Watch, then set up the shape test.

What is water resistance?

▶ Can't see it? Watch "What is water resistance? — Year 5 Forces" on YouTube

Swap the clip: change the ID after /embed/ (now sZquDi8aomw).

Say thisWater resistance is a friction force between water and a moving object. The more streamlined the shape, the less water resistance — so it moves through water more easily. Sharks and dolphins are streamlined.

🐬

Streamlinedless resistance

🧱

Bluntmore resistance

💧

A frictionacts in any liquid

We do · 1 6 min

Plan the comparative test together — same idea, new context.

Plan the water test

Change: shape of the object | Measure: time to reach the bottom | Keep same: same clay mass, same cylinder, same water

Variables again

Independent = shape · Dependent = time to sink · Controlled = mass of clay, liquid, cylinder, start point.

Use the same mass of modelling clay so only the shape changes.

I do · 2 4 min

Play the animation. Show streamlined vs blunt sinking.

Streamlined sinks faster

The streamlined shape slips down through the water; the blunt shape is held back.

Model the ruleThe streamlined shape has less water resistance, so it reaches the bottom first. The blunt shape pushes against more water and sinks slowly.

Keep the clay the same mass for each shape — otherwise the test isn't fair.

We do · 2 5 min

Rank shapes by predicted streamlining.

Most streamlined?

Predict together

teardrop · flat disc · cube · pointed cone

Which will have the least water resistance? Which the most? Give reasons.

Independent 10 min

On your own. Sort each shape/idea, then finish your plan at your tier.

Streamlined sorter

🐬 More streamlined (less resistance)

🧱 Less streamlined (more resistance)

🚫 Myth to bust

Tap a card to sort it…

🌱 Seedling

Working towards

Sort the cards. Then finish: A streamlined shape has ____ water resistance.

🌿 Sapling

Expected

Sort them, then write our plan: change… measure… keep the same…

🌳 Oak

Greater depth

Explain why we keep the mass of clay the same, and why that makes it a fair test.

Exit ticket 4 min

Answer at your tier, then hand it in.

Show what you know

🌱 Seedling

Working towards

Water resistance is a type of ____.
What does streamlined mean?

🌿 Sapling

Expected

What are we changing in the water test?
Why keep the clay the same mass?

🌳 Oak

Greater depth

Predict which shape sinks fastest and explain it using water resistance.