1 - Getting Started ~5 mins
Imagine you need to lift a heavy school bag onto a high shelf. Pushing straight up is hard work. What if a tool could change the size or direction of your push so the bag felt lighter?
Today we build two simple machines, a lever and a pulley, and feel what they do to the effort. Hands up: which do you think will make the lift feel easier?
Keep this beat light. No apparatus on desks yet. Hold up one heavy-looking bag or box and ask the class how they would get it onto a high shelf without a big struggle. Take two or three quick ideas, then name the lesson goal: we will build a lever and try a single pulley and notice what happens to the effort.
Nature of STEM cue: later we will link what they build to school examples and to cranes and lifts in Irish ports and old mill machinery. Do not front-load that story here.
Have ready nearby (not handed out yet): rulers or card strips and pencils for pivots for every group; string, cotton reels or pulley wheels, small loads, and 2–3 pre-set pulley stations (metre stick across two stable chair backs) around the room.
2 - What Is a Lever? ~7 mins
Today we start with two words.
Simple machine: a tool that changes the size or direction of a force so a job feels easier.
Lever: a stiff bar that turns on a fixed point called a pivot.
Watch the lever demo. Where should the pivot go to make the lift feel easier?
Project only the short board text above. Hold pulley and trade-off off the board until groups have felt each machine. Use the full table below for yourself.
| Concept | Why it matters | Example |
|---|---|---|
| Simple machine — a tool with few or no moving parts that changes the size or direction of a force so a job feels easier | Almost every lift, open or cut we do at home and school uses one of these ideas without us noticing | A bottle opener, a door handle, a see-saw, or a crane hook and cable |
| Lever — a stiff bar that turns on a fixed pivot so a small push at one end can lift a heavier load at the other | Moving the pivot changes how hard you push and how far your hand travels | A ruler on a pencil pivot with a book on the short end and your finger on the long end |
| Pulley — a wheel with a groove that a string runs over, used to raise a load by pulling in a new direction or with less effort | A single fixed pulley mainly changes the direction of your pull (you pull down to lift up), which is often safer and easier to control | A cotton reel on string hung over a metre stick between two chairs, lifting a small bag |
| Trade-off — when the effort you need falls, the distance you must move usually rises by about the same factor | Simple machines do not give free energy; they swap a hard short push for an easier longer one (or change direction) | Pivot nearer the load: lift feels lighter, but your hand travels further |
Modelled investigation (you do this live before groups build)
I wonder: does moving the pivot closer to the load make the lift feel easier?
I predict: yes — the book will feel lighter when the pivot is near the book and my hand is far away.
I test: rest a ruler on a pencil pivot. Put a small book on one end. Press the other end with one finger. Try the pivot near the middle, then nearer the book. Keep the same book and the same finger.
I observed: with the pivot near the book the press felt much lighter, but my finger had to push a longer way down.
I think: a lever can reduce the effort, but you pay with extra distance. Name this bargain now as the trade-off, still in spoken language only; pupils will write it later.
Misconception to head off: children often say the machine "makes free power". Stress that the work is shared differently, not removed. A single fixed pulley often feels the same effort and mainly changes direction — that is still useful (name pulley properly when groups meet the stations).
Irish link (keep brief for later): port cranes and warehouse lifts use pulleys and levers; old water mills used wheels and gear trains. We return to this at the end with named examples.
3 - Build a Lever, Then Try a Pulley ~16 mins
First: build a lever at your table.
- Rest a ruler on a pencil pivot.
- Put the small load on one end.
- Press the other end with one finger.
- Try the pivot near the middle, then nearer the load. Notice how hard you push and how far your finger moves.
Stop and try that now.
Next: try the pulley at a station.
A pulley is a wheel a string runs over.
- When your group is called, go to a pulley station.
- Tie one end of the string to the load. Pull the free end down.
- Does the load rise? Does the pull feel easier, harder, or about the same — and which way are you pulling now?
Keep loads low and stand clear if anything slips.
Default classroom plan (realistic footprint)
Do not try one metre-stick hang per group. Set up 2–3 shared pulley stations before the lesson (metre stick secured across two stable chair backs, cotton reel or pulley wheel, string ready). Every group builds and feels the lever at their own table first. Then rotate groups to a pulley station for about 2–3 minutes each while other groups keep comparing lever pivot positions or watch and predict for the group at the station.
Low-kit fallback: one pulley hang at the front; groups take turns feeling the pull while the class watches and answers your questions.
Board reveal
Show only the lever lines first. Call "stop and try" and let groups build. Only then reveal the pulley lines and call groups to stations. Name pulley as they meet the apparatus.
During the build
- Visit groups and ask them to show the pivot position that made the lever feel easiest.
- At the single fixed pulley, expect many groups to say the effort feels similar. That is correct and important: the big win is pulling down to lift up.
- If a group has a second free-moving pulley available, they may try a second loop only if kit allows; do not require it.
Safety
Loads must be light (small bag of cubes, a water bottle less than half full, or a few books). Secure each metre stick so it cannot roll off. Nobody stands under a hanging load. String ends kept short so they do not loop round necks. Chairs are supports only — nobody climbs.
4 - Compare and Agree Your Claim ~8 mins
You have already built and felt the machines. This job is different: compare carefully and agree one group claim. No writing yet.
Lever claim: with the same load, which pivot place made the push easier, and did your hand move a short way or a long way?
Pulley claim: lift the same load once by hand, then with the pulley. Are you pulling up or down on the pulley? Did the effort feel less, more, or about the same?
Agree one spoken sentence as a group: what did each machine change — the size of the force, the direction, or both?
This is the investigation heart, not a rebuild. Groups already have the machines; now they make a deliberate fair-test comparison and an oral claim. Journal recording waits until the next step.
Fair-test reminder (they can already do this): same load, same person judging the effort where possible, same starting height for the pulley lift. Change only the pivot position on the lever, or compare hand-lift versus pulley pull.
What to expect:
- Lever: pivot nearer the load → easier push, longer hand travel.
- Single fixed pulley: effort often similar to a direct lift; direction changes (pull down to lift up).
Questions while you circulate: What did you keep the same? What is the one thing you changed? If the effort fell, what did you give up? If the effort stayed about the same, what still changed?
Do not grade "right feelings". Different pupils press with different strength; the pattern across the class matters more than any one number. Listen for the group sentence so you can revoice strong claims before the record beat.
5 - Record on Your Investigation Journal Page ~10 mins
On your Investigation Journal page, record what you built and what you noticed. This is the only place you write your claim.
For each machine, note: the load, what you changed, whether the effort felt less, more, or about the same, and anything you noticed about distance or direction.
Finish with one clear sentence. Choose the stem that matches what you felt:
- Lever stem: When the effort fell, the distance my hand moved…
- Pulley stem: The effort stayed about the same, but the direction changed because…
Pupils record on the paper Investigation Journal page (ExperimentRecord type) in this lesson, not as homework. Do not describe columns or boxes on the board; say what to record, not where it sits on the page.
Put both sentence stems on the board so groups whose single fixed pulley felt the same effort are not stuck trying to force a trade-off sentence.
Look-fors:
- Load kept the same in the notes
- At least two lever pivot trials or a clear hand-lift versus pulley comparison
- A sentence that names the trade-off (effort down, distance up) or the pulley direction change when effort stayed about the same
Support: sentence starters said aloud — The lever felt easier when… My hand had to… The pulley changed…
Stretch: ask a confident group whether a machine that only changes direction is still useful, and why a crane operator might want to pull down rather than lift up.
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