TA Brief
GROW · Grip or glide? The surface challenge
Autumn 1 · Week 3 · Explore
SoWGROW Weekly - Autumn!B34, C34
- Explore friction and how it can be helpful or unhelpful.
Matches Aut1·W3. This is the Explore lesson; measured fair-testing practice develops later. Weeks 1–2 are baseline, so no taught friction is assumed.
Prior: Use everyday experience of sliding and gripping. Ask what happens when a pencil case is gently slid on a desk. No formal force definition is required at arrival.
Next: Use the explanation in Week 3 Do: choose contact surfaces for a purpose and test with a consistent method. Later fair-test lessons develop controls and repeats.
Preparation
- Display the self-contained model; print the two design cases and the results plot.
- Optional: a soft pencil case and desk tray for a gentle adult demonstration; no measurement is required.
Care and safety
- No slipping, running or rubbing skin on rough samples. No pupil use of lubricant or working brakes.
Teacher response guidance
- Arrival: the released case ordinarily slows; accept a hypothesis before teaching.
- Model: mat 24 cm, fabric 46 cm, laminate 82 cm. Mat stops it earliest under the fixed conditions.
- Tray: tray underside and mat touch. Friction resists slipping, helping the tray stay in place.
- Drawer: runner and rail touch. Too much friction resists sliding and makes opening harder; controlled lower friction helps the job.
- Smooth surfaces can still exert friction. The laminate track in the model also stops the slider.
- Model limitation: authored outputs show one controlled comparison; real pairs and conditions can differ.
Evidence of learning
Look for two contact surfaces plus an effect linked to purpose. A numerical comparison supports model reasoning; fluent reading alone is not evidence. Separate spontaneous explanation from an adult-led prompt.
Access and independence
Allow pointing to contact areas, directed arrows, spoken explanations, text or exact scribe. Reveal one case at a time. Wait before prompting and remove the word bank when it is no longer needed.
Lundy Loop
Provide a calm participation choice. Receive the chosen explanation privately if requested, name the science heard, and offer one actionable revision. The pupil completes or dictates one “What I said, and what it changed” line only after that exchange.
Arrival · What do you notice?
Receive everyday explanations. Do not score a first prediction. If pupils say “the push runs out”, keep that idea for revision after the model. Optional adult gently slides a soft case inside a tray.
Starter · One shoe. Two surfaces.
Accept dry path with grip reasoning. Avoid saying all rough surfaces always grip better. Real friction depends on both materials and conditions. The picture opens a question rather than proving a universal texture rule.
I do · Follow the contact
Model: “The rubber underside touches the mat. The slider is moving right relative to the mat. Friction acts left on this slider, so it slows after release.” State that this is a sliding example; do not generalise the arrow to every moving object.
We do · Test the model tracks
Run the controlled model with three tracks. Sample explanation: “The textured mat stopped the slider at 24 cm, earlier than the laminate at 82 cm. In this model it slowed the slider more.” Distances are authored outputs, not a classroom experiment or a measurement of friction force.
I do · Helpful depends on the job
Point precisely to pad/rim contact and hinge pin/barrel contact. Brake example intentionally concerns sliding at pad/rim, not tyre-road force direction. Lubrication can reduce unwanted friction at a hinge; pupils do not apply oil.
We do · Repair the design claim
Expected repair: “Friction can help or hinder. A brake needs friction to slow the wheel; too much friction in a hinge resists opening.” Check the pupil uses an effect, not only good/bad labels.
Independent · Your design advice
Provide both case drawings and the complete model results. Do not give the words helpful/unhelpful in advance. A new explanation, directed arrows or exact scribe counts; copying the brake example alone does not demonstrate transfer.
Exit · Use your evidence
Expected: “Smooth surfaces can still have friction; our smooth model track slowed and stopped the slider.” Adult names the actual science heard and asks for one precise addition, such as naming both surfaces. GROW uses one closure line, not a second signature or reflection form.
Misconceptions
Friction always acts backwards on a moving object. Specify sliding between the surfaces. The slider example has leftward friction; friction can also provide forward grip when walking.
Rough always means more friction; smooth means none. Keep conclusions with the tested pair and conditions. All three model tracks slow the slider.
Friction is always bad. Compare the different jobs of the brake, hinge, tray and drawer.
Sources
OpenStax · College Physics 2e, Friction
Friction resists relative motion or attempted motion between surfaces in contact; it can enable movement as well as slow sliding.
Oak National Academy · Different kinds of force
Contact forces require touching; examples distinguish friction from drag.
Review trace
Science_Teesside/Grow/v3_40min/SCI_G_W3A_Friction_Explore.html
- Replaces the blanket opposite-motion wording with friction opposing sliding between surfaces.
- Replaces isolated rough/medium/smooth buttons with a visible common-start comparison and retained evidence.
- Adds two fully supplied independent design cases and one short GROW feedback line.
- Presents model distances honestly as constructed values, with real handling an optional observation route.
Separate review copy. No live lesson or award record has been changed.