Science lesson plan · 9th grade (Year 10 in England) · 30 minutes
Force, mass and acceleration (F = ma)
Forces and motion
CCSS NGSS.HS-PS2-1England: KS4 Combined Science: Forces and motion
Objective and success criteria
Students will: Force, mass and acceleration (F = ma).
- I can answer questions on today's skill on my own, without help.
- I can explain each step and say why it works.
- I can check my answer and spot a mistake.
Before and after
Needs first: Newton's laws of motion; Mass and weight (W = mg)
Leads to: Momentum (p = m v); Circular motion and centripetal force
Materials: Force meters, Toy cars and ramps, Mini whiteboards, A diagram or short video clip of the idea, Printed student sheet (below).
Warm-up · 4 min
- Quick retrieval from earlier learning (Newton's laws of motion; Mass and weight (W = mg)). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- You push on a wall with 50 N. What force does the wall exert on you? (50 N, pushing back on you / 25 N / 100 N / 0 N) → 50 N, pushing back on youPrompt: Forces come in pairs.
- What is the weight of a 75 kg object on Earth? Use g = 9.8 N/kg. → 735 NPrompt: weight = mass × gravitational field strength (W = m g)
- Newton's laws: which statement is true? (The two forces in a Newton's third law pair act on the same object. / Heavier objects need less force to accelerate. / A resultant force makes an object accelerate. / A moving object needs a constant force to keep moving at steady speed in space.) → A resultant force makes an object accelerate.Prompt: Think about inertia, F = ma and action–reaction pairs.
Hook · 3 min
- Drop a sheet of paper and a scrunched-up sheet together and ask why one falls faster.
- Share the objective: Force, mass and acceleration (F = ma). Read the success criteria together.
I do: model it · 7 min
- Work through the example out loud, saying why you do each step, not just what you do.
- Example: What resultant force is needed to accelerate a 80 kg mass at 2.5 m/s²?
- Step 1: F = 80 × 2.5 = 200
- Step 2: So the answer is: 200 N
- Answer: 200 N
- Pause after each step and ask a student to say what comes next.
We do: guided practice · 6 min
- Do these together. Students try each step on whiteboards before you reveal it.
- Use the hints as prompts rather than giving the answer.
- What resultant force is needed to accelerate a 80 kg mass at 1.5 m/s²? → 120 NPrompt: F = m × a
- A resultant force of 400 N acts on a 800 kg object. What is its acceleration, in m/s²? → 0.5 m/s²Prompt: Rearrange F = m a to find a.
You do: independent practice · 7 min
- Students work on the student sheet. Circulate and check the first two answers of every student early.
- Students who finish: write a question of their own for a partner, with the answer.
The 6 questions are on the student sheet below, with answers in the key.
Exit ticket · 3 min
- Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
- What resultant force is needed to accelerate a 1200 kg mass at 3 m/s²? → 3600 NPrompt: F = m × a
- A 4 kg cart is pushed forward with 30 N. Friction acts backwards with 10 N. What is its acceleration, in m/s²? → 5 m/s²Prompt: First find the resultant force.
Watch out for
- Everyday meanings of words getting in the way of the science meaning: define key words explicitly.
- Remembering facts without the reason: ask "why?" and "what is the evidence?"
Support and stretch
Support
- Review first: Newton's laws of motion.
- Use concrete materials: force meters.
- Give the first step of each question, or a partly worked example to finish.
- Pair with a confident partner for the guided practice.
Stretch
- Move on to: Momentum (p = m v); Circular motion and centripetal force.
- Explain a common mistake in writing and how to fix it.
- Write a word problem that uses today's skill, then solve a partner's.
Homework and more practice
Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-9.
Free lesson plan from eurekami.com/lesson-plan-builder