Resources: A small object (such as a marble or penny), a large clear container filled with water, a mini whiteboard, modelling clay, water, a variety of clear containers (such as large bottles with the tops cut off, or large measuring cylinders) and weighing scales.
Support Handout (1): An investigation sheet for the children to record their question, predictions, variables, results and conclusion, with scaffolding to support writing their question and variables.
Core Handout (2): An investigation sheet for the children to record their question, predictions, variables, results and conclusions.
Stretch Handout (3): An investigation sheet for the children to record their question, predictions, explain their fair test controls, results and conclusions.
Challenge Handout (4): A space is provided for children to record the similarities and differences between air and water resisitance, and to draw and label the forces acting on a boat as it moves through the water (as mentioned in the plenary).
Enquiry Approach - Problem-solving
Applying prior scientific knowledge to solve problems and answer further questions.
Enquiry Skill - Interpreting and communicating results
Using information, results and data to present findings, including oral and written explanations.
Using the starter slides, recap previous learning by asking the children to describe the difference between air resistance and gravity. Gravity is the force which draws objects towards the centre of a planet, or other body; air resistance is friction which acts between the air and another object. Discuss how objects such as parachutes have large surface areas to increase the impact of air resistance.
Through the presentation, the children will learn that water resistance is a force which prevents an object from moving easily through the water. Demonstrate to the children whether air resistance or water resistance is stronger by dropping a small object, such as a marble or penny, from the same height through water and the air.
The presentation then explores the concept of streamlining by giving examples of objects or animals which are streamlined to allow them to move through air or water more quickly.
Rocket Thinking - Teacher Notes: A key question is an open-ended prompt that can facilitate discussion, address misconceptions or give children the opportunity to probe more deeply into a topic. The purpose of this question is to prompt the children to explore water resistance and what causes an object to slow down in water.
You could extend this question to discuss if and how humans would be able to adapt to live in the water fully. How would we breathe? What would be our primary source of food?
Lastly, the presentation identifies upthrust as a force that causes something to be pushed upward. The children will understand that when upthrust and gravity are balanced, objects can float on water (buoyancy).
Career Film: Take a tour around Rolls-Royce SMR's Heritage Museum in Derby to find out about Imane Holles's job. Imane works as the Senior Verification Engineer for Rolls-Royce SMR.
Expert Film: This is Imane Holles. Imane works as the Senior Verification Engineer for Rolls-Royce SMR. Listen to Imane as she explores factors which affect an object's ability to resist water.
Ask the children to investigate which shapes of clay are most resistant to water. Using modelling clay, the children can create different shapes and then time how long each shape takes to move through the water. The children should ensure they are using the same amount of modelling clay each time (keeping the mass the same).
Using the handout, ask the children to identify the variables, write a prediction and record the time each object takes to fall through the water. They should repeat each experiment 3 times and calculate an average to ensure they get an accurate result. There is a slide after the mission assignment video to support the children in finding the average. Ask them to write a conclusion to the investigation question.
Challenge Task: Using the stretch handout, ask the children to explain the similarities and differences between air and water resistance.
Discuss findings from the experiments. Compare the result times of similar shapes and discuss how having a larger sample of results may improve accuracy.
Assess the children’s understanding of all the forces covered throughout the unit by asking them to draw the forces acting on a boat as it moves through the water, using the stretch handout. They should include gravity, air resistance, water resistance, upthrust and driving force (push). Challenge the children to think about whether these are contact or non-contact forces.
Several factors affect water resistance. These are:
1. Surface Area: The surface area of an object in contact with water directly influences the amount of water resistance it experiences. A larger surface area results in more contact with water molecules, leading to increased resistance. Objects with smaller surface areas generally encounter less water resistance.
2. Shape and Streamlining: The shape of an object plays a crucial role in determining water resistance. Streamlined or hydrodynamic shapes minimise resistance by allowing water to flow smoothly around the object. Conversely, irregular or non-streamlined shapes create turbulence, increasing water resistance.
3. Speed: The speed at which an object moves through water affects the magnitude of water resistance. As speed increases, so does drag. At higher velocities, the water molecules encounter the object more frequently, resulting in greater resistance. This relationship is a key consideration in designing vehicles and watercraft for optimal performance.
4. Viscosity of Water: Viscosity refers to the thickness or "stickiness" of a fluid. The viscosity of water can influence the level of resistance. Higher viscosity water, such as that found in cold temperatures, tends to create more resistance than lower viscosity water. This factor is particularly important in polar regions and can impact marine activities.
5. Turbulence and Surface Roughness: The presence of turbulence, caused by irregularities or roughness on the surface of an object, can significantly increase water resistance. Smooth surfaces experience less turbulence and, therefore, encounter lower resistance. This principle is often considered in the design of watercraft and swimming gear.
6. Density of the Fluid: The density of the water itself affects drag. Higher-density water results in greater resistance. This is why swimming in saltwater feels different from swimming in freshwater; saltwater is denser due to the dissolved salts.
7. Density and Buoyancy of the Object: The density of the object relative to the water also plays a role. Objects that are less dense than water (buoyant) experience a combination of buoyancy and water resistance. Adjusting the buoyancy of an object can impact its overall resistance in water.
Understanding these factors is crucial in various fields, including engineering (e.g., designing efficient boats), sports (e.g., improving swimmer performance) and environmental science (e.g., studying the impact of water resistance on marine life). By considering these aspects, professionals can develop more effective designs and strategies for navigating through water.
Address
Developing Experts Limited
Exchange Street Buildings
35-37 Exchange Street
Norwich
NR2 1DP
UK
Phone
01603 273515
Email
[email protected]
Copyright 2026 Developing Experts, All rights reserved.
Unlock expert-designed lessons, resources, and assessments tailored for educators. No credit card required.
Claim Your Free Trial →
