Keep this beat light. Invite three or four quick answers (a chair scrape, rain on the window, a cough, traffic outside). Do not hand out materials or name pitch and volume yet.

Key question: If sound is something we hear, what is the thing that is actually happening to make it?

Teaser pluck (always do this): Have one elastic band already stretched over a small box. End the hook with one clean pluck so the whole class shares the same sound. Put the box aside but leave it visible on your desk so step 2 can point back to it. One pluck only.

Project only the short board text. Use the table below yourself. Point to the elastic-band box from the hook when you ask the closing question — do not open group trays yet.

Misconception to head off: many children think louder means higher. Keep pitch (high/low) and volume (loud/quiet) as two separate ideas every time you model.

Worked example — model the full cycle once before groups work (use the ruler, matching Test A):

• I wonder: Does less of the ruler hanging over the edge sound higher or lower?
• I predict: I think a shorter overhang will sound higher because the free part will wobble faster.
• I test: Hold the ruler so about 20 cm hangs over the edge, flick once, listen. Then slide it so about 10 cm hangs over, flick with the same strength, listen again. (Same ruler, same flick strength — only how much hangs over changes.)
• I observed: The shorter overhang sounded higher; I could also see a faster blur on the short free part.
• I think: Shortening how much hangs over raised the pitch. Sound starts with the vibration; changing how the ruler vibrates changes the sound we hear.

Think the cycle aloud. This model shows the inquiry cycle using length for pitch — the same path groups will use in Test A. Do not write the conclusion on the board before pupils predict for their own trials.

Nature of STEM weave (light): physicists study energy and forces. Sound is energy on the move — it starts when something vibrates and that vibration travels through the air to our ears. Keep it one sentence, not a mini-lecture.

Before this step

Print the Investigation Journal page. Set out group trays but keep them closed until the explore step.

Show both instruments once (trays stay closed)

Before anyone writes, hold up your desk box and pluck the band once so the class links the second stem to what they already heard. Then hold a ruler on the table edge with part hanging over and give one gentle flick. Name the variable in plain words: how much of the ruler hangs over the edge. Point to the free part as it twangs. Put both instruments down. Do not open group trays yet — this is a 10–15 second show-and-name only so the stems have a shared referent.

Delivery

Agree the two questions as a class. Leave the two stem predictions on the board. Pupils write predictions on the Investigation Journal page before anyone plucks or twangs in groups.

Board stems (keep visible):

• If less of the ruler hangs over the edge, the twang will be ___ because…
• If I pluck the same band harder, ___ will change because…

Predictions are never wrong; they start the science. Circulate and push for a because clause: I think… because…

Differentiation: pairs can share one spoken prediction with the teacher if writing is slow; still capture both ideas (pitch and volume) somehow on the page.

Setup

One tray per group of three or four: a small cardboard box or tissue box with two or three elastic bands of different thicknesses stretched across; one 30 cm plastic ruler; a clear edge of the table for the ruler overhang.

Noise and listening control (use this)

Agree a clear freeze signal before trays open (e.g. hand up, lights flicker, or a soft chime). Pattern for the explore beat: about 45–60 seconds of group trials, then freeze-and-listen so the room goes quiet and each group can hear one clean pluck or twang. Repeat that cycle a few times. Stagger if needed: half the groups trial while the others watch hands-off, then swap. Do not rely on "sensible volume" alone.

How to use each instrument

• Rubber-band guitar: stretch bands across the open face of the box. Pluck gently. Tighten by twisting the box or sliding a pencil under a band as a bridge. Compare thick and thin bands if you have both.
• Ruler twang: hold the ruler firmly on the table so part hangs over the edge. Flick the free end. Change only how much hangs over (e.g. about 10 cm, then about 20 cm). Keep the flick strength the same when comparing pitch.

Guiding questions while you circulate

• What is wobbling when you hear the sound?
• When the sound stops, has the wobble stopped too?
• Did you change one thing only that time?

Safety: elastic bands stay on the instruments — no shooting. Rulers stay low over the table edge. Use the freeze signal so groups can hear their own trials.

What to expect: tighter band or less ruler hanging over sounds higher; harder plucks sound louder; the band or ruler is visibly or tangibly vibrating while the sound lasts.

Close of explore: freeze signal, hands off instruments, trays stay on desks ready for the two careful tests next.

Investigation structure (first structured fair-test lesson on sound for this class)

Stop free explore cleanly with the freeze signal. Agree the path as a class so both tests fit the slot:

• Test A (pitch): everyone uses the ruler. Change only how much hangs over the edge. Keep flick strength the same. Judge higher / lower. Group choice: which two overhang lengths to compare (suggest about 10 cm and about 20 cm if they are stuck).
• Test B (volume): everyone uses one band on the box. Keep tightness the same. Change pluck strength only. Judge louder / quieter. Group choice: gentle-then-harder or hard-then-gentler order.

That shared path is the scaffold; groups still own the two length choices, the pluck order, the listening, the vibration check, and the short jot after each test.

Steps for groups (tight timing)

1. Test A: two ruler overhangs, same flick, listen and look — about 4–5 minutes including one-line jot.
2. Freeze; swap to the box.
3. Test B: same band tightness, two pluck strengths in the order the group chose — about 4–5 minutes including one-line jot.
4. If time remains, one optional extra trial only if both jots are done.

Light capture during investigate: after each test, one short line on the journal page or a sticky corner note (changed… / heard… / vibration…). This is not a full write-up — just enough so details do not blur before the observe-and-record beat.

Look-fors: pupils separate high/low from loud/quiet; they can point to the vibrating part; they catch themselves if they changed two things at once.

If a group changes two things: pause them and ask what would make the comparison unfair, then redo one clean trial.