Arduino Learning Studiorobotics pathway

R10-U4 · usually age 10 · Robot Explorers

Automated Gate Challenge

Can our design work for different vehicles?

Pilot unit plan · 5 sessions · not yet classroom-validated

Build: Automatic parking gate

An automatic parking gate: the distance sensor watches the lane right under the arm, a threshold decides, and the servo arm opens, waits and closes. Learners integrate the three, choose the threshold from measured readings, and test it like engineers, with every vehicle driving up, stopping at the line and going once the arm is up: five runs of the same approach to show it is repeatable, then five varied approach trials with vehicles of different heights and speeds.

  • Sense
  • Decide
  • 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 arranging instruction cards or blocks, predicting what happens, and testing on a kit. Short sentences, with words and pictures together.
The adult's role
An adult oversees circuits, batteries and motors.
Session
60–75 minutes
Hardware
micro:bit with MakeCode, or a similar child-friendly board. Start in the board's own simulator. A micro:bit is 3.3 V: never connect a 5 V signal straight to it.

Starts from

Builds, and what it is the input for

In the studio today

No studio lab or activity for this unit yet.

Sessions

  1. Session 1 · 60 min

    What must our gate do for every vehicle?

    Before any wiring: the parts of the system (the distance sensor across the lane under the arm, the threshold that decides, the servo arm that acts) and what the gate must do for vehicles of different heights and speeds: open while a vehicle waits at the stop line, stay open while it passes, never come down on one, and close after it has gone.

    The adult says first: “Today we plan. The gate must work for every vehicle.”

    Learner card

    1. Sensor, then decide, then the arm.
    2. Drive up. Stop at the line.
    3. Go when the arm is up.
    4. Plan five trials.
    5. Guess each one first.

    Key words (show each with a picture): system · trial · vehicle

    Timing (15 of 60 min at the screen)

    1. 10 minAway from the screen: System cards: sensor, threshold, servo arm, in the order a vehicle meets them.
    2. 15 minAway from the screen: Role-play a real barrier: drive up with a ruler, stop at the line, go once the arm is up.
    3. 10 minAway from the screen: Write the pass rule; plan the five trials with a guess for each.
    4. 15 minAt the screen: Build the gate's blocks; with the made-up 86 the open picture never shows; try 100 to see it.
    5. 10 minAway from the screen: Say why the simulator cannot test the sensor.

    In the studio

    No studio lab or activity.

    Outside the studio: MakeCode editor and its micro:bit simulator (makecode.microbit.org)

    Hands-on

    Nothing is powered: this session uses picture cards, toy vehicles and the simulator only. First, away from the screen, the group lines up the system cards (sensor, threshold, servo arm) in the order a vehicle meets them. On a taped road with a stop line and a gate line, the group role-plays a real barrier with no electronics: one learner is the gate, and each vehicle, pushed with a ruler, drives up, stops at the stop line and goes on only once the arm is up. Together they write the pass rule and plan five varied approach trials: low car slow, low car fast, tall van slow, tall van fast, and two vehicles one after the other (the second waiting 10 cm behind the first, and driving up to the stop line as soon as the first has passed the arm); slow and fast are how briskly the ruler pushes the vehicle on through. In MakeCode next, the learner builds the gate's blocks: “on start” opens; “forever” holds an “if then else” whose condition is “0 < 0” with “ping trig P1 echo P2 unit …” (cm) on the left and 12 on the right; then the open angle and “pause (ms)” 2000, else the closed angle; and after the “if then else”, “pause (ms)” 60, because the sensor needs about 50 ms for each measurement. To see which part runs in the simulator, the learner adds a “show leds” picture in “then” only. In the simulator the distance block always gives the same made-up number (86 in cm): it has no sensor, so it cannot measure. So with 12 on the right the picture never shows; with 100 on the right it shows: that checks the blocks, not the sensor. The picture comes out again before the real gate: in blocks, each “show leds” waits 400 ms, and the gate must check the sensor often.

    Starting blocks: Built from scratch: “on start” with the open angle, and “forever” holding “if then else” whose condition is “0 < 0”, the distance in cm on the left and 12 on the right, then “pause (ms)” 60.

    Evidence to collect

    A prediction for each planned trial, the learner's own short test table (Trial | Vehicle and speed | My guess) for five varied trials, and the learner's spoken explanation of what the gate must do for every vehicle, and why the simulator cannot test the sensor.

    Test table columns: Trial | Vehicle and speed | My guess

    Predict
    Before the simulator runs, the learner guesses whether the gate will show open or closed, and why.
    Debug
    If the simulator always shows closed, that is its made-up 86 at work: compare it with the number on the right of “<”.
    Reflect
    Which vehicle will be hardest for the gate, and why?

    Works towards: Integration

  2. Session 2 · 75 min

    Does the sensor see every vehicle?

    The sensor stands at the roadside on the gate line, facing across the lane at a card backboard on the post, so its beam crosses the lane right under the arm: anything under the arm reads less than the empty lane. The threshold goes between the empty lane and the farthest vehicle reading, chosen from measured readings. A 0 means no echo, and 0 is below any threshold, so the gate opens when it is unsure.

    The adult says first: “Measure first. Then choose the number that decides.”

    Learner card

    1. Read the empty lane.
    2. Read the car. Read the van.
    3. At the line, under the arm.
    4. Pick a number between them.
    5. A 0 means no echo.

    Key words (show each with a picture): threshold · lane · measure

    Timing (10 of 75 min at the screen)

    1. 10 minAway from the screen: With the board off: the sensor on the gate line under the arm, the backboard, the stop line and the keep-off line.
    2. 10 minAt the screen: The distance in “show number”; the simulator, then download.
    3. 30 minAway from the screen: Turns at the gate, one share of the readings per pair (about 7 minutes each): the empty lane; each vehicle placed with a ruler.
    4. 10 minAway from the screen: Copy the group's readings; choose the threshold between the lane and a vehicle.
    5. 15 minAway from the screen: Check every vehicle reading is below it; say how the readings set it.

    In the studio

    No studio lab or activity.

    Outside the studio: MakeCode editor and its micro:bit simulator (makecode.microbit.org)

    Hands-on

    Before the session, with the board and the holder switched off, the adult wires the sensor as in R10-U2 (VCC to the Link header's 3V, GND to GND, Trig to P1 and Echo to P2, with four female-to-female jumper wires on the header pins the adult soldered in) on the board of the gate from R10-U3. The gate's servo stays in Servo 1. The sensor stands at the roadside on the gate line, across the lane from the gate's post, facing a card backboard taped to the post below the arm 20 cm away, so its beam crosses the lane right under the arm. A stop line is taped 1 cm before the gate line, and a keep-off line 5 cm out from the sensor's face: vehicles drive between the keep-off line and the backboard, never closer to the sensor, whose blind spot is 2 to 3 cm. In the simulator first, the learner builds “forever” holding “show number” of “ping trig P1 echo P2 unit …” (cm), then downloads it (the board switched off, the micro:bit out of the board, USB in; USB out once the light on the back stops flashing, the micro:bit back in). Pairs take turns at the gate, each taking one share of the readings: the adult, with the board switched off, puts the pair's micro:bit in; the adult switches on. The readings: the empty lane; then the low car and the tall van, each placed with a ruler at the stop line, under the arm and just past it, once near the keep-off line and once near the backboard. Everyone copies the group's readings into their own table. Last, the learner chooses the threshold between the empty lane and the farthest vehicle reading, and checks that every vehicle reading, at the stop line too, is below it.

    Starting blocks: The learner's blocks from R10-U2 session 2: “forever” holding “show number” of the distance in cm.

    Pins

    P1
    distance sensor Trig
    P2
    distance sensor Echo

    Evidence to collect

    A prediction for each reading, the learner's own short test table (In the lane | My guess (cm) | Reading (cm)) for the empty lane and each vehicle at the stop line, under the arm and past it, and the learner's spoken explanation of how the measured readings set the threshold, and what a 0 does.

    Test table columns: In the lane | My guess (cm) | Reading (cm)

    Predict
    Before each reading, the learner guesses the number in cm.
    Debug
    If the empty lane reads short, the beam is catching something else: switch off, aim the sensor straight across, read again. If a vehicle at the stop line reads like the empty lane, tape the stop line nearer the gate line.
    Reflect
    Why does the threshold come from readings, not from a guess?

    ⚠ Adult checks before power-on: Nothing metal touches the micro:bit, its gold pins or the board, and nothing metal lies under it. Before the adult switches on: the micro:bit is firmly in the board, display facing the Link header, its own battery pack and USB unplugged; both switches were off while anything was plugged in or moved. The distance sensor is an RCWL-1601, sold for 3 V or 5 V but never powered from 5 V here: it runs from the Link header's 3V pin, so its Echo signal is 3.3 V. Never a 5 V-only HC-SR04. Plastic toy vehicles only near the board; nothing metal on or under it. Rewire only when unpowered: the board and the holder are switched off before any wire, motor, servo or sensor is plugged in, moved or taken out. The servo plugs into the board's Servo 1 socket (brown to GND, red to V, orange to SIG), powered by the board's battery; the micro:bit sends only the signal. Never power a servo from the micro:bit's 3V pin. The gate arm is a strip of light card: no wood, metal or sharp corners. Hands never go in the gate's path: vehicles are pushed with a ruler or rolled from a ramp behind a start line.

    Works towards: Integration

  3. Session 3 · 75 min

    Does the whole gate work together?

    Integration: the sensor, the threshold and the servo, joined in one program. Each part is tested alone first (the reading on A, the arm on B), then together, one vehicle at a time. When the whole fails, test one part at a time to find where.

    The adult says first: “Test each part alone. Then join them. Then test again.”

    Learner card

    1. A shows the distance.
    2. B moves the arm.
    3. Then the whole gate.
    4. Stop at the line.
    5. Go when the arm is up.

    Key words (show each with a picture): integrate · part · whole

    Timing (20 of 75 min at the screen)

    1. 10 minAway from the screen: Plan: the sensor alone, the arm alone, then the whole gate.
    2. 10 minAt the screen: Build the A and B checks; the simulator, then download.
    3. 15 minAway from the screen: First turns, one pair at a time (about 3 minutes each): each part alone.
    4. 10 minAt the screen: Put in the gate blocks with your threshold; the simulator, then download.
    5. 20 minAway from the screen: Second turns (about 5 minutes each): the low car, then the tall van; stop at the line, go once the arm is up.
    6. 10 minAway from the screen: Fill in the table; say how testing one part at a time helps.

    In the studio

    No studio lab or activity.

    Outside the studio: MakeCode editor and its micro:bit simulator (makecode.microbit.org)

    Hands-on

    In the simulator first, the learner builds two checks: “on button A pressed” shows the distance in cm, and “on button B pressed” sets the open angle, pauses 1000 ms and sets the closed angle. The learner downloads them (the board switched off, the micro:bit out of the board, USB in; USB out once the light on the back stops flashing, the micro:bit back in). At the pair's first turn at the gate, the adult, with the board switched off, puts the pair's micro:bit in; the adult switches on; the learner tests each part alone, predicting first: A with the empty lane and with the car at the stop line; B for the arm. Then the learner keeps the A check, takes out the B check, puts in session 1's gate blocks with the threshold from session 2, tries them in the simulator and downloads them the same way. At the pair's second turn, the learner drives the low car up with a ruler: it stops at the stop line, waits until the arm is fully up, then goes slowly on through; the learner records whether the arm was up while it waited, stayed up while it passed under, and came down after it had gone; then the same with the tall van.

    Starting blocks: The learner's own blocks from session 1, with the threshold from session 2, and the A and B checks.

    Pins

    P1
    distance sensor Trig
    P2
    distance sensor Echo

    Evidence to collect

    A prediction for each test, the learner's own short test table (Part tested | My guess | What happened) for the sensor alone, the arm alone and the whole gate with each vehicle, and the learner's spoken explanation of how testing one part at a time helped.

    Test table columns: Part tested | My guess | What happened

    Predict
    Before each test, the learner says what the part, or the whole gate, will do.
    Debug
    If the whole gate fails, go back to the part tests: if A shows the right distance and B moves the arm, check the threshold and the “<”.
    Reflect
    Why test the parts alone before the whole gate?

    ⚠ Adult checks before power-on: Nothing metal touches the micro:bit, its gold pins or the board, and nothing metal lies under it. Before the adult switches on: the micro:bit is firmly in the board, display facing the Link header, its own battery pack and USB unplugged; both switches were off while anything was plugged in or moved. The distance sensor is an RCWL-1601, sold for 3 V or 5 V but never powered from 5 V here: it runs from the Link header's 3V pin, so its Echo signal is 3.3 V. Never a 5 V-only HC-SR04. Plastic toy vehicles only near the board; nothing metal on or under it. Rewire only when unpowered: the board and the holder are switched off before any wire, motor, servo or sensor is plugged in, moved or taken out. The servo plugs into the board's Servo 1 socket (brown to GND, red to V, orange to SIG), powered by the board's battery; the micro:bit sends only the signal. Never power a servo from the micro:bit's 3V pin. The gate arm is a strip of light card: no wood, metal or sharp corners. Hands never go in the gate's path: vehicles are pushed with a ruler or rolled from a ramp behind a start line.

    Works towards: Integration

  4. Session 4 · 75 min

    Does it work every time?

    Repeatable: one pass is not proof. The same approach is run five times in a row; a gate that passes once and fails once is not finished. The pass rule: a trial passes when the arm is fully up while the vehicle waits at the stop line, stays up while any part of the vehicle is under it, and comes down only after it has gone. When a run fails, change one thing (the threshold, or where the stop line is), then run all five again.

    The adult says first: “One pass is not enough. The same run, five times.”

    Learner card

    1. Drive it the same way.
    2. Five runs in a row.
    3. Pass or fail? Write it.
    4. One change, then all five again.

    Key words (show each with a picture): repeat · pass · fail

    Timing (15 of 75 min at the screen)

    1. 10 minAway from the screen: Read the pass rule; guess how many of five runs will pass.
    2. 10 minAt the screen: The session 3 blocks in the simulator, then download.
    3. 20 minAway from the screen: First turns, one pair at a time (about 5 minutes each): five runs in a row with the pair's vehicle.
    4. 5 minAt the screen: If a run failed: one change; the simulator, then download.
    5. 20 minAway from the screen: Second turns (about 5 minutes each): all five again.
    6. 10 minAway from the screen: Fill in the table; say why five passes mean more than one.

    In the studio

    No studio lab or activity.

    Outside the studio: MakeCode editor and its micro:bit simulator (makecode.microbit.org)

    Hands-on

    In the simulator first, the learner runs the session 3 blocks once, then downloads them (the board switched off, the micro:bit out of the board, USB in; USB out once the light on the back stops flashing, the micro:bit back in). Each pair takes one vehicle (two pairs the low car, two pairs the tall van) and, at its turn, runs the same approach five times in a row, the same way each time: driven up with a ruler, stopped at the stop line, and pushed briskly on through once the arm is up; the adult, with the board switched off, puts the pair's micro:bit in; the adult switches on, and the learner predicts and records pass or fail. If any run fails, the learner says why and changes one thing in the simulator, downloaded the same way; the stop line or the sensor's aim is changed only with the board switched off. Then all five runs again, at the pair's second turn.

    Starting blocks: The learner's session 3 blocks.

    Pins

    P1
    distance sensor Trig
    P2
    distance sensor Echo

    Evidence to collect

    A prediction for each set of runs, the learner's own short test table (Run | My guess | Pass or fail) for five runs with the pair's vehicle, and the learner's spoken or written explanation of why five passes in a row mean more than one.

    Test table columns: Run | My guess | Pass or fail

    Predict
    Before each set of five, the learner guesses how many runs will pass.
    Debug
    If the same run passes and then fails, look for what changed: where the vehicle stopped, how it was pushed, or the vehicle at an angle.
    Reflect
    What made a run repeatable: the gate, or the way we drove the vehicle?

    ⚠ Adult checks before power-on: Nothing metal touches the micro:bit, its gold pins or the board, and nothing metal lies under it. Before the adult switches on: the micro:bit is firmly in the board, display facing the Link header, its own battery pack and USB unplugged; both switches were off while anything was plugged in or moved. The distance sensor is an RCWL-1601, sold for 3 V or 5 V but never powered from 5 V here: it runs from the Link header's 3V pin, so its Echo signal is 3.3 V. Never a 5 V-only HC-SR04. Plastic toy vehicles only near the board; nothing metal on or under it. Rewire only when unpowered: the board and the holder are switched off before any wire, motor, servo or sensor is plugged in, moved or taken out. The servo plugs into the board's Servo 1 socket (brown to GND, red to V, orange to SIG), powered by the board's battery; the micro:bit sends only the signal. Never power a servo from the micro:bit's 3V pin. The gate arm is a strip of light card: no wood, metal or sharp corners. Hands never go in the gate's path: vehicles are pushed with a ruler or rolled from a ramp behind a start line.

    Works towards: Repeatable trials

  5. Session 5 · 75 min

    Can our gate pass five varied approach trials?

    The prototype, an automatic parking gate, tested like engineers: five varied approach trials (low car slow, low car fast, tall van slow, tall van fast, two vehicles one after the other), each vehicle driving up, stopping at the line and going once the arm is up; each trial predicted, run once and counted. A failed trial counts.

    The adult says first: “Five trials: different vehicles and speeds. Every result counts.”

    Learner card

    1. Read the pass rule.
    2. Guess each trial.
    3. Run each trial once.
    4. Every result counts.
    5. What can it not do yet?

    Key words (show each with a picture): trial · pass · varied

    Timing (10 of 75 min at the screen)

    1. 15 minAway from the screen: Read the pass rule and the five trials; a guess for each.
    2. 10 minAt the screen: The final program in the simulator once, then download.
    3. 30 minAway from the screen: Turns at the gate, one pair at a time (about 7 minutes each): the five trials in order, each run once.
    4. 20 minAway from the screen: Explain what each trial tested and what the gate still cannot do.

    In the studio

    No studio lab or activity.

    Outside the studio: MakeCode editor and its micro:bit simulator (makecode.microbit.org)

    Hands-on

    First, away from the screen, the learner reads out the pass rule and the five trials, with a guess for each. In the simulator next, the learner runs the final program once, then downloads it (the board switched off, the micro:bit out of the board, USB in; USB out once the light on the back stops flashing, the micro:bit back in). At the pair's turn at the gate, the adult, with the board switched off, puts the pair's micro:bit in; the adult switches on. The learner runs the five trials in order, pushing each vehicle with a ruler up to the stop line and on through once the arm is up, and records each result; every trial is run once and every result counts. Last, the learner explains which part of the system each trial tested, and what the gate still cannot do (for example, see something lower than the beam).

    Starting blocks: The learner's own blocks from session 4.

    Pins

    P1
    distance sensor Trig
    P2
    distance sensor Echo

    Evidence to collect

    The unit's evidence: the learner's gate faces five varied approach trials: a prediction for each, the learner's own short test table (Trial | My guess | What happened | Pass?) for the five trials, run once each, and the learner's spoken or written explanation of which part of the system each trial tested and what the gate still cannot do.

    Test table columns: Trial | My guess | What happened | Pass?

    Predict
    Before each trial, the learner says pass or fail, and why.
    Debug
    If a trial fails, it still counts: write why, and after the five, plan one change and a new set of five.
    Reflect
    Which trial taught you most about your design, and what would you change first?

    ⚠ Adult checks before power-on: Nothing metal touches the micro:bit, its gold pins or the board, and nothing metal lies under it. Before the adult switches on: the micro:bit is firmly in the board, display facing the Link header, its own battery pack and USB unplugged; both switches were off while anything was plugged in or moved. The distance sensor is an RCWL-1601, sold for 3 V or 5 V but never powered from 5 V here: it runs from the Link header's 3V pin, so its Echo signal is 3.3 V. Never a 5 V-only HC-SR04. Plastic toy vehicles only near the board; nothing metal on or under it. Rewire only when unpowered: the board and the holder are switched off before any wire, motor, servo or sensor is plugged in, moved or taken out. The servo plugs into the board's Servo 1 socket (brown to GND, red to V, orange to SIG), powered by the board's battery; the micro:bit sends only the signal. Never power a servo from the micro:bit's 3V pin. The gate arm is a strip of light card: no wood, metal or sharp corners. Hands never go in the gate's path: vehicles are pushed with a ruler or rolled from a ramp behind a start line.

    Works towards: Integration, Repeatable trials

Materials

  • Per pair: a BBC micro:bit and its USB cable (USB micro-B at the micro:bit end)
  • A computer with a web browser for MakeCode (makecode.microbit.org); no installs needed
  • Per pair: a Kitronik Compact All-In-One Robotics Board for BBC micro:bit (stock code 5693), its Link header fitted with a 2.54 mm pin header by the adult (soldering is adult-only)
  • Kept by the adult: 4 × AA alkaline cells (1.5 V each, 6 V nominal) in a holder with a screwed-shut cover and its own on/off switch, wired by the adult to the board's power terminal block; no rechargeable cells, Li-ion, LiPo, RC or coin-cell packs
  • Pencils and paper for the test tables
  • One gate per adult, which the pairs take turns at: a 180-degree micro servo rated 4.8–6 V with its arm (horn): the Kitronik Mini 180 Degree Metal Gear Servo MG90S (stock code 2592), the servo Kitronik's board page links to, or, as Kitronik now marks it discontinued, another micro servo with the same rating, checked first by the adult; the gate from R10-U3, with its arm and post
  • On the gate's board: a 3.3 V-safe RCWL-1601 ultrasonic distance sensor, never a 5 V-only HC-SR04, and four female-to-female jumper wires
  • Light card for the backboard; masking tape for the road, the stop line, the gate line and the keep-off line
  • A low plastic toy car and a tall plastic toy van, and a 30 cm ruler to place or push them

⚠ Safety before any session

  • Batteries: only AA alkaline cells in the board's closed holder, and USB from a computer for downloads; no rechargeable cells, power banks, Li-ion, LiPo, RC packs or coin cells.
  • Cells: the adult fits four new alkaline cells of one type, the right way round, never mixes new and used cells, takes spent cells out and screws the cover shut.
  • The battery holder stays with the adult, beside the board on the adult's side; learners never handle the cells or the holder.
  • The power-off switch is the board's on/off switch: it cuts the battery to the board, the micro:bit and every motor and servo. Anyone may switch it off at any time; only the adult switches it on.
  • The servo plugs into the board's Servo 1 socket (brown to GND, red to V, orange to SIG), powered by the board's battery; the micro:bit sends only the signal. Never power a servo from the micro:bit's 3V pin.
  • The gate arm is a strip of light card: no wood, metal or sharp corners. Hands never go in the gate's path: vehicles are pushed with a ruler or rolled from a ramp behind a start line.
  • The distance sensor is an RCWL-1601, sold for 3 V or 5 V but never powered from 5 V here: it runs from the Link header's 3V pin, so its Echo signal is 3.3 V. Never a 5 V-only HC-SR04.
  • Rewire only when unpowered: the board and the holder are switched off before any wire, motor, servo or sensor is plugged in, moved or taken out.
  • Only the parts the plan names connect to the micro:bit, through the board's Link header. Never connect a 5 V signal or supply to a micro:bit's pins or battery socket: it runs at 3.6 V at most.
  • Plastic toy vehicles only near the board; nothing metal on or under it.
  • If the board, a motor, the holder or a wire gets warm: switch the board off, don't touch it, tell the adult.
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

  • Read each step aloud first: your words come before the learner's card. The card uses short sentences; show each key word with a picture.
  • These plans assume one adult for up to four pairs. Learners plug the USB cable into their own computer, gripping the plug, while the adult watches; only the adult handles cells and battery packs. With more pairs, add an adult or bring fewer pairs to the real board at once.
  • Kitronik labels the board Age 11+ and tags it Designed for_Engineers. These plans are adult-led for that reason: the adult builds, wires, powers and switches every rig and keeps the battery holder; the learner changes numbers in blocks, presses the micro:bit's buttons when the adult says, and watches from outside the safe zone or the gate's path.
  • Only one spinner or gate runs at a time near each adult. Its board sits outside the safe zone on the adult's side, with leads long enough to reach, and the adult stands at its switch as the stopper.
  • One powered rig per adult: pairs take turns at it, one pair at a time. Each pair downloads to its own micro:bit, and at the pair's turn the adult, with the board switched off, swaps it into the rig. While they wait, the other pairs predict, fill in their tables or work in the simulator, watching from outside the zone. Each session's timing counts the turns and the waiting.
  • Each session's timing keeps screen time to short bursts (15 minutes at most), with building, acting or testing away from the screen between them.
  • Before the first session on the real board, set up each computer and test a download: either pair each micro:bit once with WebUSB (then MakeCode's Download button sends the program straight to it), or download the .hex file and drag it onto the MICROBIT drive. The light on the back flashes while the program copies: unplug only after it stops.
  • To download, the board is switched off and the adult takes the micro:bit out of it (or the learner does, with the adult watching), holding it by its edges and pulling it straight out; the learner plugs in USB, downloads and unplugs USB once the light on the back stops flashing; the micro:bit goes back in the same way, straight and firmly, display facing the Link header, before the adult switches on. Every swap wears the edge connector a little: swap only to download or at a pair's turn, and never rock the micro:bit out.
  • Before the first session, add the extensions on each computer: in MakeCode's Extensions, search for Kitronik and pick the Kitronik robotics Board; for the distance sensor, search for sonar.
  • The MakeCode simulator prepares the work. Only the real board, seen working by the adult, counts as evidence: a simulator run is never physical success.
  • Learners already make their own test tables (R09-U3): give the columns, and the learner draws and fills in the table.
  • The studio's Arduino labs are written for ages 12 and up and are not used in this unit, not even its motor, servo or distance labs: they wire a 5 V Uno, never a micro:bit.
  • The pack is 6 V nominal (4 × 1.5 V), at the edge of all three ranges: the bottom of Kitronik's recommended 6.0–10.8 V for the board, and the top of the TT motor's 3–6 V and the servo's 4.8–6 V. Expect it to vary: new cells can read above 1.5 V each with nothing running (Energizer's handbook works an example with an open circuit voltage of 1.6 V), and the pack sags under load, because each fresh cell has 150 to 300 milliohms of internal resistance (Energizer E91). Kitronik's board page lists under Requires a Power Supply that links to its 3 × AA holder; these plans use 4 × AA instead, because 3 × AA is 4.5 V nominal, below the board's recommended 6.0 V and the servo's 4.8 V.
  • Check each servo before its first powered session. A servo's signal must suit its supply: the Foundation warns that at a higher supply voltage “the 3V from the micro:bit might not be enough to direct the servo”, and Kitronik's MG90S page says you may need to level shift the signal. The board's own signal level is not documented, so the adult checks: on the board at 6 V, the servo moves to 0, 90 and 180 and holds still at each. A servo that does not follow is not used.
  • A trial passes when the arm is fully up while the vehicle waits at the stop line, stays up while any part of the vehicle is under it, and comes down only after it has gone.
  • The beam crosses the lane under the arm, so the safe stop rule holds: while anything in the beam is under the arm, the reading is below the threshold and the arm stays up. Safety comes from where the beam is, never from the pause, which only keeps the arm up a moment after a vehicle has gone. The arm is still light card, because a sensor can miss things: the gate cannot see something lower than the beam.
  • In every trial the vehicle drives up, stops at the stop line and goes on only once the arm is fully up, as at a real barrier: the gate is tested on what a real barrier does, never on beating the arm.
  • The five trials of session 5 are the test, run once each: a failed trial counts and is never rerun to make a streak.
  • Runs for one adult: about 20 in session 4 (five per pair), up to 40 if every pair needs its second set; 20 in session 5 (five trials per pair).
  • The threshold comes from this gate's own readings, so no calibration against a ruler is needed here.
  • Readiness decides, not age: a learner who already joins a sensor, a threshold and a servo and tests a design with repeated trials can move on to the next band's work.

Planned studio features

Not built yet. The unit runs without them.

  • A micro:bit-style parking-gate lab in the studio, with a labelled simulated distance input and the gate arm drawn.
  • Printable picture cards for each session's key words, the system cards and printable learner cards.
  • A printable trial sheet for the five varied approach trials.

Sources

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