Forces and Motion Lesson Plan with Simulations
Updated 2026-10-02
This forces and motion lesson plan uses free simulations so students can see what a force does, and what it doesn't do, in one class period. They balance a tug of war, push a crate across ice and watch it keep going, find out how hard they must push before friction lets go, and test F = m·a with four different masses. You get goals, setup, predictions, the readings students should get, a five-question set for the class link, an extension for older students and differentiation. Every number comes from the simulations' own models.
Lesson at a glance
- Level: grades 6–9 (ages 11–15), physical science. The extension suits grades 9–10.
- Time: one 55–60 minute period, plus an optional 20-minute extension.
- Prior knowledge: force measured in newtons, speed, the idea of friction.
- Format: pairs on laptops, tablets or phones, or the whole class with one projector.
- Simulations: Forces and motion – the basics. Extension: Newton's second law – pulling a block.
Learning goals
By the end of the lesson, students can:
- Add forces along a line to find the net force, and say whether the forces are balanced.
- Explain that an object with no net force keeps moving at a steady speed (Newton's first law).
- Explain that friction matches a small push until it reaches its maximum, then the object slides.
- Use F = m·a to predict the acceleration for a given net force and mass.
- Explain why the same push gives a heavy object a smaller acceleration.
What the simulation does
The simulation has four screens, chosen with the tabs at the top.
- Net force: a tug of war. Drag people onto either side of the rope: Child (50 N), Student (100 N), Adult (150 N) or Strongman (200 N), up to four per team. The readout shows the net force and "Balanced", "Leaning left" or "Leaning right". Tap someone on the rope to remove them.
- Motion: push an object on a frictionless surface. Choose Light crate (50 kg), Heavy crate (100 kg), Fridge (150 kg) or Person (70 kg). The Push/pull force F slider runs from −400 N to 400 N in steps of 20 N. Remove force (F = 0) lets go.
- Friction: the same, plus a Friction menu: None, Low, Medium or High.
- Acceleration: adds a large F = m·a panel whose numbers grow and shrink with their values, plus an acceleration arrow.
On the object screens, the readout under the controls shows F, friction, the net force, a, v and the distance.
A few details worth knowing before class:
- Signs show direction. Forces to the left are negative. The friction readout is negative when the push is to the right, because friction points the other way.
- Each screen keeps its own settings. The force and mass you set on one screen don't carry over to the next.
- Reset puts the object back but keeps the push. Press Remove force (F = 0) as well if you want it to stay still.
- The default friction is Low on the Friction and Acceleration screens.
Materials and setup before class
Materials: one device per pair (or a projector), the tables below on paper, and a calculator.
Setup (10 minutes, once):
- Open the simulation. The defaults are fine: Net force screen, friction Low, values shown.
- Click Share and create a link for each class, for example "Science · Period 5".
- Optional: on the Questions tab, enter the question set below and attach it to the link. The two predictions lock the simulation until each student commits.
- Post the link, or open it in present mode and show the QR code. Teaching with a projector covers present mode in detail.
Lesson sequence
1. Hook and predictions (7 minutes)
Project the Net force screen. Put an Adult and a Student on the left, then ask the class who to add on the right to make it fair. Then have students commit to two predictions, on paper or on the link:
- P1. "A crate slides across a frictionless floor. You stop pushing. What does the crate do?"
- P2. "You push a 50 kg crate and a 150 kg fridge with the same 100 N, with no friction. How does the fridge's acceleration compare with the crate's?"
Most students say the crate "runs out of force" and stops. Many pick "the same" or "half" for P2. Don't correct anyone yet. The Predict–Observe–Explain guide explains why the commitment matters.
2. Net force: the tug of war (8 minutes)
Pairs build each match, read the net force and press Reset between games.
| Left team | Right team | Net force | Result |
|---|---|---|---|
| Adult + Student (250 N) | Strongman + Child (250 N) | 0 N | Balanced |
| Adult + Student + Child (300 N) | Strongman + Child (250 N) | −50 N | Leaning left, then the left team wins |
| Student (100 N) | Child + Child (100 N) | 0 N | Balanced |
Ask: "In the first match, are there no forces?" There are 500 N of pulling, but they cancel. Balanced doesn't mean no forces. The strongest possible team is four Strongmen, 800 N.
3. Motion: what happens when you stop pushing? (10 minutes)
Switch to the Motion tab and choose the Light crate.
- Set F = 100 N. The readout shows a = 2.00 m/s² and v climbing.
- After a few seconds, press Remove force (F = 0). Now a = 0.00 m/s², and v stays at whatever it had reached. The ground marks keep sliding past.
- Set F = −100 N. The crate slows down, stops for an instant, then speeds up to the left.
Check P1. With no friction and no push, nothing changes the crate's motion, so it keeps the same speed forever. That is Newton's first law. A force changes the motion; it isn't needed to keep it going.
4. Friction: how hard must you push? (12 minutes)
Switch to the Friction tab (friction Low) with the Light crate.
- Set F = 40 N. Nothing moves. The friction readout shows −40.0 N: 40 N in the opposite direction, so the net force is 0.
- Set F = 60 N. The crate slides. Friction reads −49.0 N, the net force 11.0 N and a = 0.22 m/s².
Ask: "Why did friction grow from 40 N to 49 N, then stop growing?" Friction only pushes back as hard as it needs to, up to a maximum. On Low friction the maximum is 49 N for this crate. Pairs then find the smallest push on the slider that starts each object moving:
| Object | Low | Medium | High |
|---|---|---|---|
| Light crate (50 kg) | 60 N | 160 N | 300 N |
| Person (70 kg) | 80 N | 220 N | won't move |
| Heavy crate (100 kg) | 100 N | 300 N | won't move |
| Fridge (150 kg) | 160 N | won't move | won't move |
Heavier objects press harder on the floor, so they need a bigger push. "Won't move" means the maximum friction is above 400 N, the end of the slider. For you: the maximum friction is μmg with μ = 0.1, 0.3 and 0.6 for Low, Medium and High.
Finally, push the Light crate until it slides fast, then press Remove force (F = 0). It slows down at a = −0.98 m/s² on Low and stops. Compare with step 3: friction is the force that "uses up" the motion on a real floor.
5. F = m·a on the Acceleration screen (12 minutes)
Switch to the Acceleration tab and set Friction to None, so the net force equals the push. Set F = 100 N, press Reset and read a for each mass. Then try 200 N on the Light crate.
| Object | Mass (kg) | Net force (N) | a (m/s²) | m × a (N) |
|---|---|---|---|---|
| Light crate | 50 | 100 | 2.00 | 100 |
| Person | 70 | 100 | 1.43 | 100 |
| Heavy crate | 100 | 100 | 1.00 | 100 |
| Fridge | 150 | 100 | 0.67 | 100 |
| Light crate | 50 | 200 | 4.00 | 200 |
Students fill in the last column themselves. Rounding aside, it always equals the net force. Check P2: three times the mass gives one third of the acceleration, 0.67 instead of 2.00 m/s².
Then set Friction back to Low and push the Light crate with 100 N. The F = m·a panel now shows 51 N, not 100 N, and a = 1.02 m/s². Ask why. Friction takes 49 N, and only the net force sets the acceleration.
6. Exit check (5 minutes)
Use questions 3–5 of the set below. Then open View answers and show the Prediction and After columns for P1 and P2 side by side.
Question set for this lesson
Enter these on the simulation's Questions tab. Suggested Instructions for students: "Change one thing at a time. Press Reset before each new reading. Read a from the readout under the controls."
1. Multiple choice · Before, as a prediction · Ask again after the simulation
- Question: "A crate slides across a frictionless floor. You stop pushing. What does the crate do?"
- Options: Stops at once / Slows down and stops / Keeps moving at the same speed (correct) / Speeds up
- Explanation: "With no friction and no push, the net force is zero, so nothing changes the crate's motion. It keeps the speed it had: the Motion screen shows a = 0.00 m/s² and a steady v. That is Newton's first law. Real crates stop because friction is a force."
2. Multiple choice · Before, as a prediction · Ask again after the simulation
- Question: "You push a 50 kg crate and a 150 kg fridge with the same 100 N, with no friction. How does the fridge's acceleration compare with the crate's?"
- Options: The same / Half as big / One third as big (correct) / Three times as big
- Explanation: "a = F/m. The crate gets 100 ÷ 50 = 2.00 m/s² and the fridge 100 ÷ 150 = 0.67 m/s². Three times the mass gives one third of the acceleration for the same net force."
3. Number · After the simulation
- Question: "On the Friction screen, choose the Light crate and Low friction. What is the smallest push on the slider that makes the crate slide?"
- Answer: 60, tolerance ± 1, unit N
- Explanation: "On Low friction the floor can push back with up to 49 N on this crate. A 40 N push is matched exactly, so the crate stays still. The slider moves in 20 N steps, so the first push bigger than 49 N is 60 N."
4. Number · After the simulation
- Question: "On the Acceleration screen, set Friction to None, choose the Person (70 kg) and push with 100 N. What is the acceleration?"
- Answer: 1.43, tolerance ± 0.02, unit m/s²
- Explanation: "With no friction, the net force is the full 100 N. a = F/m = 100 ÷ 70 ≈ 1.43 m/s². That is less than the 2.00 m/s² of the 50 kg crate and more than the 1.00 m/s² of the 100 kg crate."
5. Short answer · After the simulation
- Question: "You push the Light crate with 40 N on Low friction and it doesn't move. Is there a net force on it? Explain."
- Accepted answers (optional): *balanced*
- Model answer: "No. Friction pushes back with exactly 40 N, so the two forces are balanced and the net force is zero. With no net force, the crate stays at rest. Friction can only grow to 49 N, so a bigger push would make it slide."
Questions 1 and 2 are the predictions, asked again after the simulation so students can compare. The formative assessment guide explains how to read the results across classes.
Extension: Newton's second law with a graph
For grades 9–10 or fast finishers, the Newton's second law simulation pulls a block along a surface and draws its velocity–time graph live. The pulling force F has its own slider (0–50 N); students set the mass, μ and the incline angle in the Starting values panel. The readout writes the whole calculation, for example a = (F − Fms − P·sinα)/m.
Start from the defaults: F = 10 N, m = 2 kg, μ = 0.2, level surface. Then change one value at a time and press Reset:
| F (N) | m (kg) | μ | a (m/s²) |
|---|---|---|---|
| 10 | 2 | 0.2 | 3.04 |
| 20 | 2 | 0.2 | 8.04 |
| 10 | 2 | 0 | 5.00 |
| 20 | 4 | 0 | 5.00 |
| 20 | 4 | 0.2 | 3.04 |
Two questions to ask:
- "Why does doubling F from 10 N to 20 N more than double a?" Friction stays at 3.92 N (shown as 3.9 N), so the net force grows from 6.08 N to 16.08 N.
- "What does the steeper v–t graph mean?" A bigger acceleration. The force sets the slope of the graph, not the speed itself.
For a challenge, set the angle to 30°. At F = 13 N the block stays still, held by static friction; at 14 N it moves up the slope at 0.40 m/s². For motion in two dimensions, continue with the projectile motion lesson plan.
Differentiation
Support:
- Use only steps 2, 3 and 5, with friction None throughout.
- Give the tables with the objects and forces filled in, so students only read and record.
- Give sentence starters: "When the forces are balanced, the object…" and "A bigger mass gives a… acceleration."
Stretch:
- Predict the whole step 5 table from F = m·a before measuring.
- Calculate the maximum friction for each cell of the step 4 table and explain every "won't move".
- On the Acceleration screen with Medium friction, find the push that gives the Heavy crate a = 1.06 m/s² (400 N: 400 − 294 = 106 N, and 106 ÷ 100 = 1.06).
English learners: the simulation is available in six languages. Create a second link in the student's language so the labels are familiar while the discussion stays in English.
Standards alignment
This lesson supports NGSS MS-PS2-2: plan an investigation to provide evidence that the change in an object's motion depends on the sum of the forces on the object and the mass of the object. It also fits the forces topic of GCSE Combined Science and the start of a high school physics course.
For more ideas in this unit, see interactive physics lesson ideas. For general classroom routines, see how to use interactive simulations in the classroom.
FAQ
Why does the crate on the Motion screen never stop?
The Motion screen has no friction at all, like a puck on perfect ice. With no net force, the speed never changes. Use the Friction screen to show why real objects stop.
Why is the friction readout negative?
Forces to the right are positive and forces to the left are negative. When the push is to the right, friction points left, so its value has a minus sign.
Can students do this lesson on phones?
Yes. Students open the link without an account. The slider and the buttons work on touch screens; dragging people onto the rope is easier on a tablet or laptop.