Fluids and Forces

Overview

In this lesson (Lesson 11 of 15) you will explore how different forces can change the motion of fluids. Students will investigate fluid movement through simple, safe experiments and connect their observations to force and motion concepts.

Learning intentions

• Students will investigate how forces can cause changes in fluid movement.
• Students will describe how pushing, pulling, or pressure differences affect fluid flow.
• Students will use evidence from observations to explain cause-and-effect relationships in fluids.

Success criteria

• I can describe the effect of a force (such as pushing or pressure changes) on how a fluid moves.
• I can collect and record observations from a fluid experiment using clear data tables.
• I can use scientific language to explain why my observations occurred.
• I can communicate my findings clearly to a partner or small group.

Curriculum links

• Forces affecting motion in everyday contexts, including fluids
• Scientific inquiry skills: form questions, make predictions, conduct safe investigations, and record/interpret results
• Communication of findings using evidence and appropriate scientific terms

Lesson structure (45 minutes)

1. 3 Activate prior learning (discussion + quick review) Ask: “What are fluids, and how can they move?” Review from earlier lessons: fluid flow, pressure, and how changes in conditions can move fluids. Students turn-and-talk for 1 minute, then share one idea.

2. 5 Set up the focus question and “I can” goals State the lesson focus: “How do different forces change fluid movement?” Students write (or dictate) an “I can” statement in their notebooks: “I can describe the effects of force on fluid movement.”

3. 12 Mini-lesson: Force → fluid motion (teacher modelling) Use a simple demonstration (or teacher-led setup) showing a pressure/force difference causing movement (e.g., squeezing a syringe with water, tipping a bottle to change flow direction, or using a pipette to create flow). Emphasize cause-and-effect: “When force changes, the movement of the fluid changes.”

4. 20 Student investigations in pairs (two stations or one rotation) Provide 2–3 short, safe experiment options and let groups choose one to focus on (teachers can run stations to manage materials). Example options aligned to the focus:

• Squeezing syringe / pipette force: Students vary how strongly they squeeze (gentle vs firm) and observe flow speed/stream thickness.
• Raising vs lowering water source: Students change the “height/pressure” by using different starting heights and observe changes in flow rate.
• Fan/airflow on a water stream: Students observe how adding air movement changes the path of a flowing stream (where safe and appropriate). Students record: what force they used, what they observed (direction, speed, stream size), and any patterns.

5. 3 Whole-class evidence check (gallery walk prompts) Groups display their recorded observations (or hold up notebooks). Prompt: “What changed because you changed the force?”

6. 2 Conclusion: construct an explanation sentence Students complete a sentence stem: “When we applied ___ to the fluid, the fluid ___ because ___.”

7. 0–0 Wrap-up (exit ticket instructions) Exit ticket: one paragraph or 2–3 dot points answering: “Describe how force affects fluid movement, using evidence from your experiment.”

Resources

• Water in small containers or cups (enough for each pair)
• Disposable syringes without needles, pipettes, or droppers
• Clear plastic tubing (optional), small trays/containers to catch spills
• Measuring cylinders or rulers (for approximate comparisons)
• Data recording sheets or notebooks
• Paper towels and safety goggles
• Timer (phone timer allowed) for measuring “time to deliver” or stream duration (optional)
• Student-friendly science vocabulary cards (pressure, force, flow, direction, speed)
• Exit ticket slips

Assessment

• Observation checklist during investigations: correct recording, safe practices, and use of cause-and-effect language.
• Review of student data tables/notes for clarity and completeness.
• Exit ticket for understanding: a claim supported by evidence from their experiment.

Differentiation

• Support for ESL learners:
• Provide sentence frames: “We applied…”, “We observed…”, “This happened because…”
• Pre-teach key terms with visuals (force = push/pull image, pressure = “squeezing” image, flow = “movement of fluid” arrow).
• Allow oral recording first (partner talk), then students write or copy key phrases.
• Support for students needing scaffolds:
• Give a partially completed data table template with headers already filled.
• Use a “2-observation minimum” rule (each student records at least two clear observations).
• Extension for advanced learners:
• Challenge: propose an additional test (e.g., changing angle or distance) and predict the outcome before trying.
• Ask for a more detailed explanation linking force/pressure to change in motion.
• SEN considerations:
• Reduce writing load by allowing short phrases, diagrams, or numbered steps.
• Assign clear roles in pairs (materials manager, recorder, reporter) to support participation.

Unit/long range plan (context: Understanding Fluids in Science)

This lesson sits within a 15-lesson unit. Below is a practical unit breakdown that a teacher can use alongside the current lesson sequence.

• Lesson 1: What are fluids? Properties and examples (water, air, gases and liquids).
• Lesson 2: Fluid particles and why fluids flow (introduction to motion at the particle level).
• Lesson 3: Pressure basics in fluids using everyday examples.
• Lesson 4: How pressure differences can move fluids (simple demonstrations).
• Lesson 5: Flow rate and what affects it (height/pressure, pathway).
• Lesson 6: Direction and path of flow (constraints, channeling).
• Lesson 7: Forces and motion review in the context of fluids.
• Lesson 8: Investigating force-driven movement (designing a fair test).
• Lesson 9: Comparing results across trials (data interpretation and uncertainty).
• Lesson 10: Applications in the real world (plumbing, hydraulics, environmental flow).
• Lesson 11: Force and Motion in Fluids (current lesson: experiments with different forces).
• Lesson 12: Planning and conducting a longer investigation (student inquiry).
• Lesson 13: Communicating findings (reports, graphs/tables, explanations).
• Lesson 14: Review and synthesis: linking force, pressure, and fluid movement.
• Lesson 15: Unit assessment and reflection on learning growth.

Lesson sequence for the day (what you teach)

• Learning focus: describe how force affects fluid movement.
• Students investigate and gather evidence, then write an explanation using a sentence stem.
• Exit ticket confirms understanding of force → fluid movement using experiment evidence.