R07-U2 · usually age 7 · Little Inventors

Wheels and Steering

What makes a vehicle turn?

Pilot unit plan · 4 sessions · not yet classroom-validated

Build: Steerable rolling vehicle

What makes a vehicle turn: a card car whose front wheels sit on a steering plate that turns on one pin. Children set the steering straight or turned, predict the path, let the car roll from a low ramp, and compare a straight path and a curve fairly; then a short and a long car, and wheels that grip.

Act
Test and debug

Who it is for

Age is a starting point, never a limit. A learner who can show what this unit starts from can begin here at any age.

How they learn: By making, moving and playing: ramps, wheels, levers, a classmate acting as a robot. Pictures and arrows instead of words; no code text.
The adult's role: An adult leads every session and prepares anything powered. Children never handle loose batteries, sharp tools or hot parts.
Session: 45–60 minutes
Hardware: No controller needed: cardboard, wheels, gears; optional enclosed low-voltage modules. The adult prepares or checks any wiring. No loose batteries, coin cells, small magnets, sharp tools or hot parts.

Starts from

Wheels and axles
Explain why wheels and axles make moving easier, and compare two designs.
Built in R06-U2 Roll, Slide and Balance
Fair comparison
Compare two designs fairly: change one thing at a time.
Built in R06-U2 Roll, Slide and Balance

Builds, and what it is the input for

Steering
Make a vehicle go straight and turn on purpose.
Input for R07-U4 Rescue Vehicle Workshop, R11-U1 Build the Rover

In the studio today

No studio lab or activity for this unit yet.

Sessions

Session 1 · 50 min
What makes a vehicle turn?
Wheels roll the way they point. A car goes straight when its front wheels point straight, and curves when they are turned. Steering is turning the front wheels on purpose.
The adult says first: “Wheels roll the way they point. Watch the car. Straight or curve?”
Picture cards for the children (symbols and drawings; they read nothing)
1. ⬆ — picture: a car going straight
2. ↰ — picture: a car curving left
3. ↱ — picture: a car curving right
4. ◁ ▷ — picture: the steering tab pointing left or right
Key words (said aloud, pointing to the card): steer · straight · curve
Timing (0 of 50 min at the screen)
1. 10 minAway from the screen: Walk and turn by pointing feet; show with hands which way a wheel points.
2. 10 minAway from the screen: The adult shows the car, its steering plate and the three lines on its nose.
3. 20 minAway from the screen: Three runs: straight, left, right; guess with a card before each.
4. 10 minAway from the screen: Each child shows with their hands how the wheels pointed for a curve.
In the studio
No studio lab: this session is off-screen.
Hands-on
Nothing is powered. First the children walk slowly in a line and turn by pointing their feet, then show with their hands which way a wheel points. Then the adult shows the example car, a card box car the adult builds before the session: each axle a dowel turning in a drinking-straw bushing taped to the card, so the wheels spin freely; its back wheels under the box, its front wheels on a steering plate under the nose that turns on one split pin (holes made by the hole rule, the pin pushed through, flattened and taped by the adult); a steering tab, part of the plate, sticks out in front of the pin, so the wheels point the way the tab points (tab to the left, the car curves left); three lines drawn on the nose: straight, left and right. On the ramp (its top raised by one book about 3 cm thick (or two, about 6 cm, if the adult's trial needs it), no higher than 20 cm, the run-out on carpet or a rug), the adult sets the tab straight, presses a masking-tape tab over it and lets the car go from the start line; then turned left, then turned right. Before each run the children hold up the straight card or the curve card.
Evidence to collect
The adult's note of each child's straight-or-curve guesses and what each run did, and a photo of the example car with its tab on each line (car only).
Predict
Before each run, every child holds up the straight card or the curve card for the way the tab points.
Debug
If a straight car curves, look at the tab: is it really on the straight line, and is the tape holding it? Set it again and let go from the line.
Reflect
How did the car know which way to go?
⚠ Adult checks: Holes: only the adult makes them, at a side table, with a single-hole punch (near an edge) or a sharp pencil pushed through the card into a blob of modelling clay (further in). The punch and the pencil stay at the adult's side table, out of the children's reach. Split pins are small and pointed: the adult keeps the box, flattens each pin's legs and tapes over the ends, and counts the pins out and back in. Fitted pins stay under the adult's check: before each session, and before a build leaves the table, the adult checks every pin is flat, taped and tight. Ramps sit on the floor, never on a table. The top is no higher than 20 cm, a soft catch wall at least 100 cm from the foot stops anything that rolls that far, and nobody sits in the run-out lane. Distance runs (planning choices): the top raised by one book about 3 cm thick or by two (about 6 cm), the run-out on carpet or a rug, the catch wall moved back to 200 cm. The adult does a trial run before the session: if both reach the wall, lower the ramp. The adult tries each car first: it should roll at least about 60 cm on the run-out. If not, raise the top to two books (about 6 cm) or lay a smooth board or card sheet, edges taped flat. A turned car may roll off the ramp's side: the top is only one or two books high, so it drops a few centimetres onto the carpet. Nobody sits beside the ramp. Steering runs: a clear run-out area at least 2 m wide on carpet or a rug, tape edges pressed flat; everyone sits behind the ramp's top or outside the area's edge.
Works towards: Steering
Session 2 · 55 min
Can I make it go where I choose?
Turning on purpose: each pair sets the steering, guesses where the car will stop, and lets it go. A fair test: the same ramp, the same start line, let go, no pushing; only the steering changes.
The adult says first: “Set the steering. Guess where it stops. Let go at the line.”
Picture cards for the children (symbols and drawings; they read nothing)
1. ⬆ — picture: the tab on the straight line
2. ↰ ↱ — picture: the tab on the left or right line
3. ▬ — picture: a strip of tape where it stopped
4. = — picture: the same start line every time
Key words (said aloud, pointing to the card): steer · same
Timing (0 of 55 min at the screen)
1. 10 minAway from the screen: The adult shows how to set the tab and tape it, and where to sit.
2. 30 minAway from the screen: Each pair runs straight, left and right; tape where each stops.
3. 10 minAway from the screen: Compare the three marks: where did each setting send the car?
4. 5 minAway from the screen: The adult photographs the marks, no children in the frame.
In the studio
No studio lab: this session is off-screen.
Hands-on
Nothing is powered. Each pair has a card box car the adult builds before the session: each axle a dowel turning in a drinking-straw bushing taped to the card, so the wheels spin freely; its back wheels under the box, its front wheels on a steering plate under the nose that turns on one split pin (holes made by the hole rule, the pin pushed through, flattened and taped by the adult); a steering tab, part of the plate, sticks out in front of the pin, so the wheels point the way the tab points (tab to the left, the car curves left); three lines drawn on the nose: straight, left and right. The ramp's top is raised by one book about 3 cm thick (or two, about 6 cm, if the adult's trial needs it), no higher than 20 cm, the run-out is on carpet or a rug, and everyone sits behind the ramp's top or outside the run-out area. A child turns the tab to the straight line and presses a masking-tape tab over it, then lets the car go from the start line, without pushing; the partner puts a strip of tape on the floor where it stops, only after it has stopped and nothing else is let go. Then left, then right, each with its own tape strip.
Evidence to collect
A photo of each pair's three tape marks with the car beside them (no children in the frame), and the adult's note of where each pair guessed the car would stop.
Predict
Before each run, the pair points to the place on the floor where they think the car will stop.
Debug
If two runs with the same setting stop far apart, check the start line, the let-go (no push) and that the wheels spin freely in their straws, then run both again. If both reach the wall, lower the ramp.
Reflect
What one thing did you change, and what stayed the same?
⚠ Adult checks: Holes: only the adult makes them, at a side table, with a single-hole punch (near an edge) or a sharp pencil pushed through the card into a blob of modelling clay (further in). The punch and the pencil stay at the adult's side table, out of the children's reach. Split pins are small and pointed: the adult keeps the box, flattens each pin's legs and tapes over the ends, and counts the pins out and back in. Fitted pins stay under the adult's check: before each session, and before a build leaves the table, the adult checks every pin is flat, taped and tight. Ramps sit on the floor, never on a table. The top is no higher than 20 cm, a soft catch wall at least 100 cm from the foot stops anything that rolls that far, and nobody sits in the run-out lane. Distance runs (planning choices): the top raised by one book about 3 cm thick or by two (about 6 cm), the run-out on carpet or a rug, the catch wall moved back to 200 cm. The adult does a trial run before the session: if both reach the wall, lower the ramp. The adult tries each car first: it should roll at least about 60 cm on the run-out. If not, raise the top to two books (about 6 cm) or lay a smooth board or card sheet, edges taped flat. A turned car may roll off the ramp's side: the top is only one or two books high, so it drops a few centimetres onto the carpet. Nobody sits beside the ramp. Steering runs: a clear run-out area at least 2 m wide on carpet or a rug, tape edges pressed flat; everyone sits behind the ramp's top or outside the area's edge.
Works towards: Steering
Session 3 · 55 min
Does a long car turn like a short car?
The wheelbase is the distance between the front and back axles. With the same steering, a short car (axles 10 cm apart) turns a tighter curve than a long car (20 cm apart). Wheels grip: they roll forwards, but slide only with a push from the side.
The adult says first: “Same steering, two cars. Which one turns the tighter curve?”
Picture cards for the children (symbols and drawings; they read nothing)
1. ▭ — picture: a short car
2. ▭▭ — picture: a long car
3. ↰ ↰ — picture: both cars set to turn left
4. ➡ ⬆ — picture: a car rolling forwards, not sideways
Key words (said aloud, pointing to the card): wheelbase · grip · curve
Timing (0 of 55 min at the screen)
1. 10 minAway from the screen: Grip: push a car forwards, then from the side; what happens?
2. 10 minAway from the screen: The adult shows the short and the long car; guess which turns tighter.
3. 25 minAway from the screen: Both cars set to the left line, let go from the start line; tape each stop.
4. 10 minAway from the screen: Compare the marks; the adult photographs them, no children in the frame.
In the studio
No studio lab: this session is off-screen.
Hands-on
Nothing is powered. The adult has built two cars like the session 2 cars, a short one (axles 10 cm apart) and a long one (20 cm apart), and tried them first: if their curves look the same, the adult draws the turn lines further round and tries again. Grip first: each child gently pushes a car forwards on the table, then from the side, and says which way it rolled. Then on the ramp (one book about 3 cm thick (or two, about 6 cm, if the adult's trial needs it), no higher than 20 cm, the run-out on carpet or a rug), both cars set to the left line, each let go from the start line in turn; a child tapes where each stops, only after it has stopped and nothing else is let go.
Evidence to collect
A photo of the short and the long car beside their tape marks (cars only), and the adult's note of each child's guess and what they saw.
Predict
Before the runs, each child points to the car they think will turn the tighter curve.
Debug
If the two cars curve the same, check both tabs are on the same line and both cars were let go, not pushed, then run them again.
Reflect
Why might a long bus need more room to turn a corner than a small car?
⚠ Adult checks: Fitted pins stay under the adult's check: before each session, and before a build leaves the table, the adult checks every pin is flat, taped and tight. Ramps sit on the floor, never on a table. The top is no higher than 20 cm, a soft catch wall at least 100 cm from the foot stops anything that rolls that far, and nobody sits in the run-out lane. Distance runs (planning choices): the top raised by one book about 3 cm thick or by two (about 6 cm), the run-out on carpet or a rug, the catch wall moved back to 200 cm. The adult does a trial run before the session: if both reach the wall, lower the ramp. The adult tries each car first: it should roll at least about 60 cm on the run-out. If not, raise the top to two books (about 6 cm) or lay a smooth board or card sheet, edges taped flat. A turned car may roll off the ramp's side: the top is only one or two books high, so it drops a few centimetres onto the carpet. Nobody sits beside the ramp. Steering runs: a clear run-out area at least 2 m wide on carpet or a rug, tape edges pressed flat; everyone sits behind the ramp's top or outside the area's edge.
Works towards: Steering
Session 4 · 55 min
Can we test a straight path and a curve?
Each pair shows that they can make their car go straight and turn on purpose: a straight path to a star ahead, and a curve to a star on one side, from the same start line.
The adult says first: “Straight to one star. A curve to the other. Show me how.”
Picture cards for the children (symbols and drawings; they read nothing)
1. ⬆ ★ — picture: a car going straight to a star
2. ↱ ★ — picture: a car curving to a star at the side
3. ▬ ▬ — picture: two tape marks on the floor
Key words (said aloud, pointing to the card): straight · curve · test
Timing (0 of 55 min at the screen)
1. 10 minAway from the screen: The adult checks the pins and tapes the two stars; pairs practise setting the tab.
2. 25 minAway from the screen: Each pair runs straight, then a curve; tape where each stops.
3. 15 minAway from the screen: Show and tell: which setting sent the car to which star, and why.
4. 5 minAway from the screen: The adult photographs each car beside its marks, no children in the frame.
In the studio
No studio lab: this session is off-screen.
Hands-on
Nothing is powered. The adult checks every steering pin is flat, taped and tight, and tapes two paper stars flat on the run-out: one straight ahead, one off to one side. The ramp's top is raised by one book about 3 cm thick (or two, about 6 cm, if the adult's trial needs it), no higher than 20 cm, the run-out on carpet or a rug. Each pair sets the tab straight, says where the car will stop, and lets it go from the start line; the partner tapes where it stops, only after it has stopped and nothing else is let go. Then the pair chooses the tab line that should curve towards the side star, and does the same. Each pair shows the adult their two tape marks and says why each went where it did. After the session the cars stay in the setting: the adult takes them apart and counts every split pin back in.
Evidence to collect
The unit's evidence: each pair tests a straight path and a curve with their car (the tab straight, then turned towards the side star), from the same start line, shown and told to the adult; kept as the adult's note and a photo of the car beside its two tape marks, never of the children.
Predict
Before each run, the pair points to the star they think the car will stop nearest.
Debug
If the curve misses the side star, the pair chooses the other turn line or checks the tab's tape, and runs it again. If a car reaches the wall, lower the ramp.
Reflect
How would you steer a real rescue vehicle round a corner?
⚠ Adult checks: Fitted pins stay under the adult's check: before each session, and before a build leaves the table, the adult checks every pin is flat, taped and tight. Builds with split pins stay in the setting: after the last session the adult takes them apart and counts every split pin back in. Ramps sit on the floor, never on a table. The top is no higher than 20 cm, a soft catch wall at least 100 cm from the foot stops anything that rolls that far, and nobody sits in the run-out lane. Distance runs (planning choices): the top raised by one book about 3 cm thick or by two (about 6 cm), the run-out on carpet or a rug, the catch wall moved back to 200 cm. The adult does a trial run before the session: if both reach the wall, lower the ramp. The adult tries each car first: it should roll at least about 60 cm on the run-out. If not, raise the top to two books (about 6 cm) or lay a smooth board or card sheet, edges taped flat. A turned car may roll off the ramp's side: the top is only one or two books high, so it drops a few centimetres onto the carpet. Nobody sits beside the ramp. Steering runs: a clear run-out area at least 2 m wide on carpet or a rug, tape edges pressed flat; everyone sits behind the ramp's top or outside the area's edge. Photos are of the build only, taken by the adult on the setting's device, following its photo policy: no child in the frame, no names visible, the build on the table or floor, not in a hand. Nothing is uploaded to this studio and no name goes into it; the adult's notes follow the setting's records policy.
Works towards: Steering

Materials

Per group of up to six: a big cardboard box of prepared parts (pre-cut by the adult), masking tape, glue sticks, crayons and large sheets of paper for drawings
Small scissors with rounded, blunt ends for every child, with left-handed pairs
The adult's picture cards for the session, drawn large (drawn by hand today; printable cards are planned)
A ramp of stiff card about 1 m long, two books about 3 cm thick to raise its top (never above 20 cm), a soft catch wall (a cushion against a box) and carpet or a rug for a run-out area at least 2 m wide; a smooth board or card sheet for the run-out if the adult's roll trial needs it
Card box cars built by the adult before each session: one per pair, the example car, and a short and a long car (axles 10 and 20 cm apart); card wheels at least 6 cm across on wooden dowels with rounded ends, each dowel turning in a short drinking-straw bushing taped to the card; a steering plate the adult fits on one split pin, its tab in front of the pin; three lines on the nose
A box of split pins (paper fasteners), kept by the adult
A single-hole punch, or a sharp pencil and a blob of modelling clay, kept at the adult's side table
Masking tape for the steering tabs and the stop marks, and two paper stars

⚠ Safety before any session

Nothing in these units is powered: no batteries, no plugs, no controller. Every machine is pushed, pulled or turned by hand.
Ramps sit on the floor, never on a table. The top is no higher than 20 cm, a soft catch wall at least 100 cm from the foot stops anything that rolls that far, and nobody sits in the run-out lane.
Distance runs (planning choices): the top raised by one book about 3 cm thick or by two (about 6 cm), the run-out on carpet or a rug, the catch wall moved back to 200 cm.
The adult does a trial run before the session: if both reach the wall, lower the ramp.
The adult tries each car first: it should roll at least about 60 cm on the run-out. If not, raise the top to two books (about 6 cm) or lay a smooth board or card sheet, edges taped flat.
A turned car may roll off the ramp's side: the top is only one or two books high, so it drops a few centimetres onto the carpet. Nobody sits beside the ramp.
Steering runs: a clear run-out area at least 2 m wide on carpet or a rug, tape edges pressed flat; everyone sits behind the ramp's top or outside the area's edge.
Small parts: nothing loose, or that could come off, that fits inside the small-parts cylinder (31.70 mm wide, 57.10 mm long). No beads, marbles, buttons, small magnets or coin cells. If in doubt, leave it out.
The one exception is split pins, which stay under the adult's check.
No craft knives, box cutters or pointed scissors near the children: the adult cuts thick card before the session, away from them, and only the adult makes holes (see the hole rule).
Scissors: only small scissors with rounded, blunt ends, used sitting down, with left-handed scissors for left-handed children. Children cut paper and thin card only.
Holes: only the adult makes them, at a side table, with a single-hole punch (near an edge) or a sharp pencil pushed through the card into a blob of modelling clay (further in).
The punch and the pencil stay at the adult's side table, out of the children's reach.
Split pins are small and pointed: the adult keeps the box, flattens each pin's legs and tapes over the ends, and counts the pins out and back in.
Fitted pins stay under the adult's check: before each session, and before a build leaves the table, the adult checks every pin is flat, taped and tight.
Builds with split pins stay in the setting: after the last session the adult takes them apart and counts every split pin back in.
Photos are of the build only, taken by the adult on the setting's device, following its photo policy: no child in the frame, no names visible, the build on the table or floor, not in a hand.
Nothing is uploaded to this studio and no name goes into it; the adult's notes follow the setting's records policy.

Safety for every band

Low voltage only: battery packs or USB. Never mains electricity.
Never connect a motor straight to a controller pin: use a driver and a separate supply.
Every moving robot has a power-off switch within reach that cuts the motor battery (or all power). A software stop button is extra, never a replacement.
No coin or button cells and no loose small magnets; battery compartments screwed shut.
Guard wheels and moving parts against pinched fingers; keep robots slow and indoors.
No exposed lithium cells, improvised chargers or lasers.
No Li-ion, LiPo or RC packs: AA alkaline or NiMH cells in a closed holder with a switch, or USB.
Check polarity and voltage before power-on; a 3.3 V board must not receive 5 V signals.

Notes for the adult

Say each step aloud: your words come first. The children read nothing. Each session's picture cards show symbols and drawings only; say the key word as you point to its card.
These plans assume one adult for up to six children. The adult leads every step, prepares every cut before the session, makes every hole (by the hole rule) and keeps the craft box and the split pins.
With a whole class, run a carousel: one station of up to six children run by the adult, and independent stations within the adult's sight where the others have a defined task with no scissors, split pins or ramps (each plan's “Whole class:” note names them). Groups swap until every child has been at the adult's station.
Whole class: the ramp and the cars stay at the adult's station. The independent stations are drawing a car going straight and a car curving, with arrows, and drawing where they think a short and a long car will stop.
Inclusion: every child takes part. Mobility: a child can show a movement their own way (hands, arms or a large soft toy), be the robot on big, clear squares in a wheelchair, lay the cards or give the instructions, or move a large soft toy across a table-top grid. Vision: large, high-contrast or tactile picture cards (raised outlines). Hearing: say each key word and point to its card at the same time, facing the child. Left-handed children get left-handed scissors with rounded ends.
In this unit, a child who cannot reach the floor sets the tab at a table and gives the let-go signal while a partner lets the car go; a child who cannot see the marks feels the tape strips on the floor.
Evidence is showing and telling: a demonstration, a photo of the build (never of a child, no names visible) or a drawing that you keep, or your own short note. No names in the studio, no scores, no uploads.
The CPSC's small-parts rule is written for toys for children under 3, and it exempts paper and writing materials such as crayons (16 CFR 1501.3, quoted). These plans apply its cylinder check to the loose objects children handle, and to anything that could come off, a stricter planning choice: groups mix ages and younger visitors come in. Paper and crayons stay in use; the adult collects glue-stick caps and crayon stubs at the end of each session.
No screen in this unit: every session is away from the screen. Robot Instructions has no level for it.
The ramp's one-book slope (two if needed), the carpet run-out, the 2 m run-out area, the 60 cm roll, the straw bushings and the 10 and 20 cm wheelbases are this plan's own choices. Build the example car first and try every setting, so that the straight and the turned runs clearly end in different places. A card car on carpet from a 3 cm slope may stop short: that is what the roll trial is for.
Which way the car turns follows from the plate, reasoned rather than measured: the tab is part of the steering plate and sticks out in front of the pin, so turning the tab turns the wheels the same way. Tab to the left, the wheels point left and the car curves left.
Split pins are small parts with pointed ends, so only you handle them: keep the steering pins' legs flattened and taped, check them before each session, and take the cars apart yourself at the end.
This unit relies on wheels and axles and on a fair comparison (R06-U2): the same ramp, the same start line, let go, change one thing. It does not teach them again.
Readiness decides, not age: a child who already makes a car go straight and turn on purpose has what R07-U4 needs from this unit.

Planned studio features

Not built yet. The unit runs without them.

Printable picture cards: straight, left and right, the steering tab, short and long cars, the stars.
A printable car template: the box, the steering plate and the wheels, with every hole and the three steering lines marked, for the adult to cut from card.

Sources

The facts this plan relies on, in each source's own words.

US CPSC: Child Safety: Summary Information for Small Parts, 16 C.F.R. Part 1501
“A small part is any object that fits completely into a specially designed test cylinder 2.25 inches /57.10mm long by 1.25 inches /31.70 mm wide that approximates the size of the fully expanded throat of a child under three years old. … A piece of a toy or article that breaks off during testing that simulates use or abuse by children. … Toys and games that are or contain small parts as manufactured and that are intended for use by children from 3 to 6 years old must be labeled to warn purchasers not to buy them for children under 3 years old because those children could choke on the small parts. Marbles, small balls, and balloons require similar warnings.”
US eCFR, 16 CFR 1501 (a CPSC rule): Method for identifying toys and other articles intended for use by children under 3 years of age which present choking, aspiration, or ingestion hazards because of small parts
“This regulation does not apply to toys or articles which are solely intended for use by children 3 years of age or older. … The following articles are exempt from this regulation … Books and other articles made of paper; … Writing materials such as crayons, chalk, pencils, and pens; … Any components or pieces (excluding paper, fabric, yarn, fuzz, elastic, and string) which have become detached from the article as a result of the use and abuse testing shall be placed into the cylinder, one at a time.”
US eCFR, 16 CFR 1500.48 (a CPSC rule): Technical requirements for determining a sharp point in toys and other articles intended for use by children under 8 years of age
“The sharp point test prescribed by paragraph (d) of this section will be used by the Commission in making a preliminary determination that points on toys and other articles intended for use by children under 8 years of age, and such points exposed in normal use or as a result of reasonably foreseeable damage or abuse of such toys and articles, present a potential risk of injury by puncture or laceration”
NHS (Gateshead Health NHS Foundation Trust): Scissor Skills
“Children may have the skills to use small scissors by three to four years of age, but scissor skills are not fully developed until 6 years of age. … Children will need supervision for sharp scissors. Make sure that scissors have rounded rather than pointy ends for safety. … Always provide left handed scissors for left handed children. … Start with thick solid lines to cut.”
UK HSE: Slips and trips, causes and prevention: overview
“The majority of trips are caused by obstructions in walkways. … It is not just good enough to have a walkway, it must be kept clear, no trailing wires, no obstructions.”