R07-U4 · usually age 7 · Little Inventors

Rescue Vehicle Workshop

Can we build a machine for a mission?

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

Build: Mechanical rescue vehicle

Building a machine for a mission: each team turns a rescue mission into goal cards and limit cards (pictures), builds a rescue vehicle from a steerable card car, a tray and the tongs, tests it on a marked floor route, changes one thing, and moves a light, soft payload through the route.

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

Steering
Make a vehicle go straight and turn on purpose.
Built in R07-U2 Wheels and Steering
Levers and gears
Use a lever or gears to lift or turn something more easily.
Built in R07-U1 Levers and Gears
Try again
Change one thing and try again after a failure.
Built in R06-U3 Robot Instructions

Builds, and what it is the input for

Criteria and constraints
Turn a mission into goals and limits (criteria and constraints).
Input for R09-U4 Smart Crossing, R12-U4 Solve a Local Problem

In the studio today

No studio lab or activity for this unit yet.

Sessions

Session 1 · 50 min
What does our rescue machine need to do?
A mission becomes goals (what the machine must do) and limits (what we must keep to). The adult tells the mission; the team sorts picture cards onto a goal mat (✓) and a limit mat (⛔).
The adult says first: “Here is our mission. Which cards are goals? Which are limits?”
Picture cards for the children (symbols and drawings; they read nothing)
1. ★ ⬅ — picture: the soft toy reaching the safe zone
2. ● ▭ ✓ — picture: the soft toy still on the tray
3. ▢ ▢ ↔ — picture: the vehicle fitting between the gate's two boxes
4. ▭ ✂ ⛔ — picture: only the team's card and tape, no new parts
5. ✓ ⛔ — picture: the goal mat and the limit mat
Key words (said aloud, pointing to the card): goal · limit · mission
Timing (0 of 50 min at the screen)
1. 10 minAway from the screen: The adult tells the mission with the soft toy and the route.
2. 20 minAway from the screen: Teams sort the goal and limit cards onto the two mats.
3. 15 minAway from the screen: One team at a time walks beside the route and tries the gate.
4. 5 minAway from the screen: The adult photographs each team's cards, no children in the frame.
In the studio
No studio lab: this session is off-screen.
Hands-on
Nothing is powered. The adult tells the mission: a soft toy waits at the start and must reach the safe zone along the taped route, through a gate of two light, empty boxes 30 cm apart. The adult lays the goal cards and the limit cards in a mixed pile; each team of three or four sorts them onto the goal mat or the limit mat, then says each card aloud with the adult. Then the teams walk slowly beside the route, one team at a time, and try the gate with their hands, without stepping over or past its boxes.
Evidence to collect
A photo of each team's sorted goal and limit cards (cards only), and the adult's note of which cards each team placed and why.
Predict
Before the walk, each team points to the part of the route they think will be hardest for a vehicle.
Debug
If a card lands on the wrong mat, ask: is it something the machine must do, or something we must keep to? Move it and say why.
Reflect
Which goal will be hardest to meet, and why?
⚠ Adult checks: Route: tape lines 40 cm apart on a clear floor away from doors and walkways, every edge pressed flat; one team on it at a time. The pusher walks behind on a long handle, or kneels. The gate is two light, empty boxes. Nobody steps over them or squeezes past them: the vehicle goes through, the team walks round. Loads are light and soft, at least 6 cm across: a soft ball, a clean sponge, a scrunched-paper ball or a soft toy with no buttons or beads.
Works towards: Criteria and constraints
Session 2 · 55 min
How will our vehicle meet the goals?
The team plans and builds: a steerable car, a tray with low walls to keep the payload on (a low load tips less), a push handle and the tongs. Each goal and limit card is checked against the plan.
The adult says first: “Plan your vehicle. Check every card. Load the toy with the tongs.”
Picture cards for the children (symbols and drawings; they read nothing)
1. ✋➡ ↱ ✓ — picture: the pusher, the steerer and the checker
2. ▭ ▢ — picture: a tray with low walls on a car
3. ▢ ▢ ↔ — picture: the vehicle fitting between the gate's two boxes
4. ⋀ ✓ — picture: the tongs loading the toy, no hands
Key words (said aloud, pointing to the card): plan · team · check
Timing (0 of 55 min at the screen)
1. 15 minAway from the screen: Each team draws its plan around the car on a large sheet.
2. 25 minAway from the screen: Tape on the tray and the push handle; decorate; choose roles.
3. 10 minAway from the screen: The checker tests each limit card; load the toy with the tongs.
4. 5 minAway from the screen: The adult photographs each plan and vehicle, the build only.
In the studio
No studio lab: this session is off-screen.
Hands-on
Nothing is powered. Before the session the adult builds one card box car per team, with its steering plate on one split pin (holes made by the hole rule, the pin flattened and taped by the adult), and a pair of tongs (two card strips taped at one end). Each team draws its plan around the car on a large sheet and marks how wide its tray must be; the adult trims each box lid to the mark (thick card is the adult's to cut). The team tapes on the box-lid tray with low walls and a long push handle (a card tube about 70 cm long, made by the adult), and decorates it with crayons. Team roles, as picture cards: the pusher, the steerer and the checker. The checker holds each limit card up to the vehicle: does it fit between the gate's boxes? Then the team loads the soft toy with the tongs and checks it stays on.
Evidence to collect
A photo of each team's plan drawing and its vehicle on the table (the build only), and the adult's note of which cards the team checked.
Predict
Before loading, the team says whether the soft toy will stay on the tray when the vehicle moves.
Debug
If the vehicle is too wide for the gate, the team changes the plan, not the gate: the team marks a narrower tray, the adult trims the box lid, and the checker tries the limit card again.
Reflect
Which card made you change your plan?
⚠ 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. 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. Loads are light and soft, at least 6 cm across: a soft ball, a clean sponge, a scrunched-paper ball or a soft toy with no buttons or beads.
Works towards: Criteria and constraints
Session 3 · 55 min
Does it meet our goals?
A test run against the goal cards: the checker puts a ✓ or ✗ beside each goal. The team chooses one change, makes it, and runs again.
The adult says first: “Run the route. Tick each goal. Change one thing. Run again.”
Picture cards for the children (symbols and drawings; they read nothing)
1. ★ ⬅ — picture: the soft toy reaching the safe zone
2. ● ▭ ✓ — picture: the soft toy still on the tray
3. ‖ ✓ — picture: the wheels between the two tape lines
4. ✓ ✗ — picture: a tick and a cross beside a goal card
5. ➕ 1 — picture: one change for the next run
Key words (said aloud, pointing to the card): test · change · goal
Timing (0 of 55 min at the screen)
1. 10 minAway from the screen: The adult checks the pins; teams practise loading with the tongs.
2. 20 minAway from the screen: First runs, one team at a time; the checker lays ✓ or ✗ cards.
3. 15 minAway from the screen: Each team chooses one change and makes it.
4. 10 minAway from the screen: Second runs; the adult photographs the cards, 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. One team at a time on the route: the team loads the soft toy with the tongs, the steerer sets the tab straight, and the pusher walks slowly behind the vehicle, pushing its long handle (or kneels and pushes). At the curve mark the team stops, the steerer sets the tab to the turn line, and the pusher goes on through the gate to the safe zone, where the team unloads the toy with the tongs. The checker lays a ✓ or ✗ card beside each goal card. Then the team chooses one change (a lower tray, a different turn line, a slower push), makes it, and runs again.
Evidence to collect
A photo of each team's goal cards with their ✓ and ✗ before and after the change (cards only), and the adult's note of the change the team chose and why.
Predict
Before the first run, the checker points to the goal card the team thinks it will miss.
Debug
If the toy falls off, look at where: on the curve, at the gate, or at the start? Change only one thing for the next run.
Reflect
Which goal did your change help, and how do you know?
⚠ Adult checks: Route: tape lines 40 cm apart on a clear floor away from doors and walkways, every edge pressed flat; one team on it at a time. The pusher walks behind on a long handle, or kneels. The gate is two light, empty boxes. Nobody steps over them or squeezes past them: the vehicle goes through, the team walks round. 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. Loads are light and soft, at least 6 cm across: a soft ball, a clean sponge, a scrunched-paper ball or a soft toy with no buttons or beads.
Works towards: Criteria and constraints
Session 4 · 55 min
Can our vehicle complete the mission?
The rescue mission: each team moves the payload through the marked route and shows, card by card, which goals and limits it met.
The adult says first: “The mission: bring the toy to the safe zone. Show us your cards.”
Picture cards for the children (symbols and drawings; they read nothing)
1. ★ ⬅ — picture: the soft toy reaching the safe zone
2. ▢ ▢ — picture: the vehicle going through the gate
3. ✓ ✗ — picture: the cards ticked or crossed
Key words (said aloud, pointing to the card): mission · goal · limit
Timing (0 of 55 min at the screen)
1. 10 minAway from the screen: The adult checks the pins; teams get ready at the start.
2. 30 minAway from the screen: Each team runs the mission; the checker lays the cards.
3. 10 minAway from the screen: Each team tells one thing that worked and one to change.
4. 5 minAway from the screen: The adult photographs each vehicle and its cards, 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. Each team in turn, the others sitting outside the route's lines: the team says which goals it expects to meet, loads the soft toy with the tongs, and the pusher walks behind the vehicle on its long handle (or kneels); the team steers straight, stops at the curve mark to set the turn line, sends the vehicle through the gate while the team walks round it and unloads the toy in the safe zone with the tongs. The checker lays a ✓ or ✗ beside each goal and limit card, and the team tells the group one thing that worked and one thing they would change. After the session the vehicles stay in the setting: the adult takes them apart and counts every split pin back in.
Evidence to collect
The unit's evidence: each team moves a lightweight payload (the soft toy) through the marked route, from the start through the gate to the safe zone, shown to the group with each goal and limit card ticked or crossed; kept as the adult's note and a photo of the vehicle and its cards, never of the children.
Predict
Before its run, each team says which goals it expects to meet.
Debug
If the vehicle leaves the lines, the team stops, sets the tab again, and goes on from where it left the route.
Reflect
If you had one more session, which goal or limit would you work on, and how?
⚠ Adult checks: Route: tape lines 40 cm apart on a clear floor away from doors and walkways, every edge pressed flat; one team on it at a time. The pusher walks behind on a long handle, or kneels. The gate is two light, empty boxes. Nobody steps over them or squeezes past them: the vehicle goes through, the team walks round. 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. Loads are light and soft, at least 6 cm across: a soft ball, a clean sponge, a scrunched-paper ball or a soft toy with no buttons or beads. 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: Criteria and constraints

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)
One card box car per team, built by the adult before session 2, with a steering plate on one split pin and three steering lines on its nose (as in R07-U2); box lids for trays, trimmed by the adult, and a long push handle per team (a card tube about 70 cm long, its ends taped smooth)
A pair of tongs per team (two card strips taped at one end), made by the adult
A soft toy with no buttons or beads, at least 6 cm across, as the payload
The route: masking-tape lines 40 cm apart on a clear floor, with a start, a curve mark, a gate of two light, empty boxes 30 cm apart and a safe zone
Goal and limit picture cards, a goal mat (✓) and a limit mat (⛔), and team-role cards
A box of split pins (paper fasteners), kept by the adult, and 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.
Route: tape lines 40 cm apart on a clear floor away from doors and walkways, every edge pressed flat; one team on it at a time. The pusher walks behind on a long handle, or kneels.
The gate is two light, empty boxes. Nobody steps over them or squeezes past them: the vehicle goes through, the team walks round.
Loads are light and soft, at least 6 cm across: a soft ball, a clean sponge, a scrunched-paper ball or a soft toy with no buttons or beads.
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.
Moving parts: fingers stay out of joints and gaps while a linkage moves; move it slowly by its handle.
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 route and the vehicles stay at the adult's station, one team at a time. The independent stations are drawing the team's vehicle on the route, and drawing a new goal card for a harder mission.
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 every team role can be done sitting: the steerer sets the tab at a table, the checker lays the cards, and a child who uses a wheelchair can push the long handle from behind the vehicle.
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 goal cards (criteria) are the mission's goals: the soft toy reaching the safe zone; the soft toy still on the tray; the wheels between the two tape lines; the tongs loading the toy, no hands. The limit cards (constraints) are what the team keeps to: the vehicle fitting between the gate's two boxes; only the team's card and tape, no new parts; pushed slowly by its handle, walking pace.
The route's 40 cm lane, its 30 cm gate of light, empty boxes and the 70 cm push handle are this plan's own choices: wide enough for a card car, narrow enough that the gate limit matters. Clear the floor first; the HSE notes that most trips are caused by obstructions in walkways.
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 vehicles apart yourself at the end.
This unit relies on steering on purpose (R07-U2), the tongs (R07-U1) and changing one thing to try again (R06-U3). It does not teach them again.
Readiness decides, not age: a child who already turns a mission into goals and limits has what R09-U4 needs from this unit.

Planned studio features

Not built yet. The unit runs without them.

Printable picture cards: the goal and limit cards, the two mats and the team roles.
A printable route guide: the lane, the curve mark, the gate and the safe zone, with their sizes.

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.”