R06-U2 · usually age 6 · Little Inventors

Roll, Slide and Balance

Why do some objects move more easily?

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

Build: Cardboard rolling-ramp experiment

Why some things move more easily: rolling and sliding down a low cardboard ramp, wheels and rollers, slopes, and whether a load tips over. Children guess first, then compare two designs fairly by changing one thing, marking where each run stops with tape.

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

Kinds of movement
Show and name ways things move: push, pull, roll and spin.
Built in R06-U1 Machines Around Us
Predict and test
Predict what will happen, test it, and say what happened.
Built in R06-U1 Machines Around Us

Builds, and what it is the input for

Wheels and axles
Explain why wheels and axles make moving easier, and compare two designs.
Input for R07-U2 Wheels and Steering
Fair comparison
Compare two designs fairly: change one thing at a time.
Input for R07-U1 Levers and Gears, R07-U2 Wheels and Steering

In the studio today

No studio lab or activity for this unit yet.

Sessions

Session 1 · 50 min
What rolls and what slides?
Some things roll down a slope, some slide and some stay still. Round things roll; flat-bottomed things slide or stay still. The ramp is low, on the floor, with a soft catch wall.
The adult says first: “Let go at the line. No pushing. Will it roll or slide?”
Picture cards for the children (symbols and drawings; they read nothing)
1. ●➡ — picture: a ball rolling down a ramp
2. ▭➡ — picture: a tub sliding down a ramp
3. ▭ ⏸ — picture: a block staying still on the ramp
4. | — picture: the start line at the top of the ramp
Key words (said aloud, pointing to the card): roll · slide · ramp
Timing (0 of 50 min at the screen)
1. 10 minAway from the screen: The adult shows the ramp, the start line, the catch wall and where to sit.
2. 25 minAway from the screen: Six objects: guess with the roll, slide or stays-still card, let go, then sort.
3. 10 minAway from the screen: The roll, slide and stays-still groups: what do the rolling things share?
4. 5 minAway from the screen: The adult photographs the two groups of objects, no children in the frame.
In the studio
No studio lab: this session is off-screen.
Hands-on
Nothing is powered. The adult sets up a cardboard ramp on the floor, its top no higher than 20 cm (a stack of books under one end), its top face covered with shiny card or a laminated sheet, with a soft catch wall (a cushion against a box) at least 100 cm from its foot. Before the session the adult tries every object, so that at least one (usually the tub) really slides; if none does, the adult raises the top a little, still no higher than 20 cm. Children sit beside the ramp, never in the run-out lane. One at a time, a child lets go of an object at the top line, without pushing: a soft ball, a cardboard tube on its side, a wooden block, a smooth plastic tub upside down, a small box and the tube standing up. Before each run, everyone holds up the roll card, the slide card or the stays-still card.
Evidence to collect
The adult's note of each child's guesses and what each object did, and a photo of the objects sorted into a roll group, a slide group and a stays-still group (objects only).
Predict
Before each run, every child holds up the roll card, the slide card or the stays-still card for the object at the top.
Debug
If an object both rolls and slides, let go of it again more gently: did a push at the start change it?
Reflect
What do the things that rolled have in common?
⚠ Adult checks: 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. Balls: soft and at least 6 cm across, well over the 44.4 mm small-ball size. No marbles.
Works towards: Wheels and axles
Session 2 · 55 min
Do wheels make moving easier?
A box pushed on the floor, the same box on cardboard-tube rollers, and a toy car with wheels and axles. Wheels and rollers turn instead of rubbing along the floor. A fair test: the same ramp, the same start line, let go, no pushing.
The adult says first: “Same ramp, same line, let go. Which goes further: the box or the car?”
Picture cards for the children (symbols and drawings; they read nothing)
1. ▢ — picture: a box on the ramp
2. 🚗 — picture: a toy car on the ramp
3. ▬ — picture: a strip of tape where it stopped
4. = — picture: the same start line for both
Key words (said aloud, pointing to the card): wheel · axle · fair
Timing (0 of 55 min at the screen)
1. 10 minAway from the screen: Push a box on the floor, then on cardboard-tube rollers: which is easier?
2. 25 minAway from the screen: The ramp: the box and the toy car, let go from the line; tape where each stops.
3. 15 minAway from the screen: Compare the tape marks; the adult shows the wheels and the axle.
4. 5 minAway from the screen: The adult photographs the marks, no children in the frame, and notes what each child said.
In the studio
No studio lab: this session is off-screen.
Hands-on
Nothing is powered. First, on the floor, each child gently pushes a small box along, then the same box on three cardboard tubes as rollers, and says which was easier. Then on the ramp, its top raised by one book about 3 cm thick (always no higher than 20 cm), the run-out on carpet or a rug and the catch wall moved back to 200 cm: the box, then the toy car, each let go from the start line without pushing. A child puts a strip of masking tape on the floor where each one stops, only after it has stopped and nothing else is let go. The adult points to the wheels and the axle they turn on.
Evidence to collect
A photo of the two tape marks with the box and the car beside them (no children in the frame), and each child's spoken answer: which went further, and why.
Predict
Before the ramp runs, each child points to the box or the car: which will stop further away?
Debug
If a run looks unfair (a push, or a start behind the line), say so and run it again from the line. If both reach the wall, lower the ramp.
Reflect
Where have you seen wheels or rollers make something easier to move?
⚠ Adult checks: 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 rollers are cardboard tubes much bigger than the small-parts cylinder.
Works towards: Wheels and axles, Fair comparison
Session 3 · 55 min
Does the slope change how far it goes?
A low slope and a slightly steeper one (one book, about 3 cm, then two, about 6 cm, never above the height limit). Change one thing only: the same car, the same start line, let go. Balance: a load placed high or low on the car, and whether it tips.
The adult says first: “We change one thing: the slope. Everything else stays the same.”
Picture cards for the children (symbols and drawings; they read nothing)
1. 📕 — picture: one book under the ramp
2. 📕📕 — picture: two books under the ramp
3. ▮ ▬ — picture: a tall tower and a flat tower on a car
Key words (said aloud, pointing to the card): slope · same · tip
Timing (0 of 55 min at the screen)
1. 10 minAway from the screen: Guess: one book or two, which car stops further away?
2. 20 minAway from the screen: Run the car from the line with one book, then two; tape each stop.
3. 15 minAway from the screen: Balance: the tower car, standing then flat, on the low slope.
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 run-out is on carpet or a rug and the catch wall is moved back to 200 cm. With one book about 3 cm thick under the ramp's top, a child lets go of the toy car at the line; another child tapes where it stops, only after it has stopped and nothing else is let go. With two books (about 6 cm, still no higher than 20 cm), the same car and the same line, again. Then balance: the adult tapes a tall cardboard tower onto the car, then lays it flat instead; children guess which way it tips or stays up, and try each on the low slope.
Evidence to collect
A photo of the tape marks for one book and two books, and of the tower car standing and lying flat (no children in the frame), and each child's spoken comparison.
Predict
Before each run, the children point to where on the floor they think the car will stop.
Debug
If two runs on the same slope stop far apart, check the start line and the let-go, then run both again. If both reach the wall, lower the ramp (thinner books).
Reflect
What was the one thing we changed, and what stayed the same?
⚠ Adult checks: 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 tower is light card, taped by the adult; nothing heavy sits on the car.
Works towards: Fair comparison, Wheels and axles
Session 4 · 60 min
Which of our two designs works better?
The children make card wheels for a box car (round wheels and square wheels on the same axle) and compare the two designs on the same ramp, or compare two slopes with their best car.
The adult says first: “Two designs, one ramp. Guess which goes further, then show me.”
Picture cards for the children (symbols and drawings; they read nothing)
1. ● ● — picture: a box car with round wheels
2. ■ ■ — picture: a box car with square wheels
3. ✂ — picture: rounded-end scissors cutting along a thick line
4. ▬ ▬ — picture: two tape marks on the floor
Key words (said aloud, pointing to the card): design · compare
Timing (0 of 60 min at the screen)
1. 15 minAway from the screen: Cut two round and two square wheels along thick lines; the adult fits them.
2. 25 minAway from the screen: Run both designs from the same line; tape where each stops.
3. 15 minAway from the screen: Each pair shows and tells: which design went further, and why.
4. 5 minAway from the screen: The adult photographs both designs beside their tape marks, no children in the frame.
In the studio
No studio lab: this session is off-screen.
Hands-on
Nothing is powered. Before the session the adult cuts the box cars from thick card, makes the axle holes and cuts the axles (paper straws or wooden dowels with rounded ends), and pre-punches the centre of every wheel on the wheel sheet (round and square wheels drawn with thick lines on thin card), all by the hole rule. At the adult's station, each pair cuts out two round wheels and two square wheels along the thick lines, with rounded-end scissors. The adult fits the wheels with tape. On the ramp (its top raised by one book about 3 cm thick, no higher than 20 cm, the run-out on carpet or a rug), each pair runs both designs from the same line, letting go, and tapes where each stops, only after it has stopped and nothing else is let go. Then each pair shows the adult their two tape marks and says which design went further.
Evidence to collect
The unit's evidence: each pair compares at least two wheel or slope designs (round and square wheels, or two slopes) from the same start line, shown and told to the adult; kept as the adult's note and a photo of both designs beside their tape marks, never of the children.
Predict
Before the runs, each pair points to the design they think will stop further from the ramp.
Debug
If a wheel rubs on the box, the adult moves it out a little on its axle, then the pair runs that design again. If both designs reach the wall, lower the ramp.
Reflect
If you made a third design, what one thing would you change?
⚠ Adult checks: 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. 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). 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. 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.
Works towards: Wheels and axles, Fair comparison

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 with its top face covered in shiny card or a laminated sheet, books (one about 3 cm thick) to raise one end to at most 20 cm, a soft catch wall (a cushion against a box), and carpet or a rug for the run-out
A soft ball at least 6 cm across, cardboard tubes, a wooden block, a smooth plastic tub, small boxes and a toy car with wheels too big for the small-parts cylinder
Box cars cut from thick card by the adult, with axle holes made and axles cut (paper straws or wooden dowels with rounded ends)
A wheel sheet for each pair: round and square wheels drawn with thick lines on thin card, each centre pre-punched by the adult (drawn by hand today; a printable wheel sheet is planned)
A single-hole punch, or a sharp pencil and a blob of modelling clay, kept at the adult's side table

⚠ 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.
Balls: soft and at least 6 cm across, well over the 44.4 mm small-ball size. No marbles.
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.
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.
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).
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.
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 cutting stay at the adult's station. The independent stations are drawing what rolled, slid or stayed still, and colouring the wheel sheet's shapes before they are cut.
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.
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.
A fair test is the idea to say again and again: the same ramp, the same line, let go, no pushing. Change one thing only.
The ramp's height limit, the one- and two-book slopes for distance runs, the 6 cm ball, the catch wall's distances and the carpet run-out are this plan's own choices, set well inside what is safe for a group on the floor, and low enough that runs stop before the wall.
Readiness decides, not age: a child who already compares two designs fairly has what R07-U1 and R07-U2 need from this unit.

Planned studio features

Not built yet. The unit runs without them.

Printable picture cards: roll, slide and stays still, the start line, one and two books, round and square wheels.
A printable wheel sheet: round and square wheels in thick lines, with each centre marked for the adult to pre-punch.
A printable ramp sheet: two lanes to mark where each design stopped, for the adult to photograph (the sheet only, never a child).

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 1500.19 (a CPSC rule): Misbranded toys and other articles intended for use by children
“Small ball means a ball that, under the influence of its own weight, passes, in any orientation, entirely through a circular hole with a diameter of 1.75 inches (44.4 mm.) in a rigid template 1⁄4 inches (6 mm.) thick. … Marble means a ball made of a hard material, such as glass, agate, marble or plastic, that is used in various children's games, generally as a playing piece or marker. … Any toy or game intended for children who are at least three years old but less than eight years of age that contains a small ball shall bear the following cautionary statement: … Any marble intended for children three years of age or older shall bear the following cautionary statement:”
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.”
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”