Conductor and dancers

Students make a conductor micro:bit that plays a tune phrase by phrase and sends a radio cue as each phrase starts; robots dance the move for each cue, so the dance keeps in time with the music.

Robotics challenges · Talk · about 50 minutes · Open the student lesson

Classroom resources

Load these into Waypoints Prepare: choose Load URL and paste the copied address, or download the file and import it. In Prepare, the worksheet's Teacher edition shows the answers; the student copy hides them.

Slides Download Present from the browser, or export to PowerPoint or PDF.
Worksheet Download Print the student copy; the Teacher edition has the answers.

Students will be able to

I can send a radio cue at the moment a phrase of music starts.
I can make a robot do a different move for each cue it receives.
I can explain why playing music until done keeps the cues in time.

Timing

Predict and Run 8 min · Investigate 10 min · Modify 12 min · Make 15 min · Real robot 5 min (optional)

Before class

This is the performance strand: lesson 2's dance moves (functions) plus lesson 7's radio. Each phrase is a function that sends its cue, then plays its notes until done. Because the music waits, the next phrase (and its cue) only starts when the last one ends, so cues arrive in time with the tune. Dancers decide what each cue means in on radio received.

Lily's show is the key slip: in background starts the music and moves on at once, so all the cues are sent together. In the simulator, two micro:bits and two robots appear (radio); pressing A on one makes the other robot dance, because a micro:bit never hears its own messages. Students need sound on (or headphones, which are not always available: the moves still show the timing).

Notes are written as letters with - for a rest, at 120 beats per minute. With real hardware, one bare micro:bit can conduct a whole class of robots in one group. Untested on real hardware: whether the robot start block errors on a micro:bit that is not in a robot (if so, the conductor's copy leaves it out). MOVE Motor classes can dance with Kitronik blocks in the same functions.

Running the lesson

Predict: the key is that cue 2 waits for phrase A's music to end.
Run: sound on if possible. Watch the second robot, and notice the first one stays still.
Investigate: Lily's show is the background-music slip. Ask: what does 'until done' make the program wait for?
Modify: phraseC is a copy of phraseB with new notes and cue 3; the dancer needs a branch for 3.
Make: let students choose any tune; keep phrases short (about 8 notes) so the moves fit.
Real robot (optional): one conductor, many dancers, one radio group: a class performance.

The hard part (on purpose)

Timing cues by playing each phrase until done. When moves happen at once, ask whether the music plays until done or in the background.

When students get stuck

What you will see	A question to ask	The fix
The robot does every move at once.	Is the music playing until done or in the background?	Use play … until done, so the next cue waits for the phrase to finish.
Nothing dances.	Which micro:bit did you press A on, and which robot are you watching?	Watch the other robot; check both use the same radio group.
A move runs on the wrong phrase.	Does each phrase send its own number, and does the dancer check that number?	Match the cue in each phrase to the branch in on radio received.

Answers to the checks

Predict: You press A on the first micro:bit. When does the second robot spin?
When the second phrase starts. phraseA plays its music until done, and only then does phraseB send cue 2, so the spin starts with the second phrase.
The quiet robot: Why does the first robot (the conductor's) not dance?
A micro:bit never hears its own radio messages, so it never receives the cues
The cues come from the first micro:bit, and a micro:bit never receives its own messages. Any other micro:bit in the group, and its robot, would dance.
Lily's show: Lily changed the music to play in the background. Now her robot does all its moves at once, before the tune reaches phrase 2. Why?
In the background, the program does not wait for the music, so cue 2 is sent straight after cue 1
'in background' starts the music and moves on at once. phraseB runs straight away and sends cue 2, so the robot gets both cues together. 'until done' waits for each phrase to finish.

Solutions

One possible solution for each task. Other correct programs are fine.

Modify › Up above the world

Show as code

function wiggle () {
    robot.motorTank(50, -50, 300)
    robot.motorTank(-50, 50, 300)
    robot.motorStop()
}
function spin () {
    robot.motorTank(50, -50, 1200)
    robot.motorStop()
}
function shuffle () {
    robot.motorTank(50, 50, 300)
    robot.motorTank(-50, -50, 300)
    robot.motorStop()
}
function phraseA () {
    radio.sendNumber(1)
    music.play(music.stringPlayable("C C G G A A G - ", 120), music.PlaybackMode.UntilDone)
}
function phraseB () {
    radio.sendNumber(2)
    music.play(music.stringPlayable("F F E E D D C - ", 120), music.PlaybackMode.UntilDone)
}
function phraseC () {
    radio.sendNumber(3)
    music.play(music.stringPlayable("G G F F E E D - ", 120), music.PlaybackMode.UntilDone)
}
input.onButtonPressed(Button.A, function () {
    phraseA()
    phraseB()
    phraseC()
})
radio.onReceivedNumber(function (receivedNumber) {
    if (receivedNumber == 1) {
        wiggle()
        wiggle()
    } else if (receivedNumber == 2) {
        spin()
    } else if (receivedNumber == 3) {
        shuffle()
        shuffle()
    }
})
robot.elecfreaksCuteBot.start()
radio.setGroup(1)

Modify › Light show

Show as code

function wiggle () {
    robot.motorTank(50, -50, 300)
    robot.motorTank(-50, 50, 300)
    robot.motorStop()
}
function spin () {
    robot.motorTank(50, -50, 1200)
    robot.motorStop()
}
function shuffle () {
    robot.motorTank(50, 50, 300)
    robot.motorTank(-50, -50, 300)
    robot.motorStop()
}
function phraseA () {
    radio.sendNumber(1)
    music.play(music.stringPlayable("C C G G A A G - ", 120), music.PlaybackMode.UntilDone)
}
function phraseB () {
    radio.sendNumber(2)
    music.play(music.stringPlayable("F F E E D D C - ", 120), music.PlaybackMode.UntilDone)
}
function phraseC () {
    radio.sendNumber(3)
    music.play(music.stringPlayable("G G F F E E D - ", 120), music.PlaybackMode.UntilDone)
}
input.onButtonPressed(Button.A, function () {
    phraseA()
    phraseB()
    phraseC()
})
radio.onReceivedNumber(function (receivedNumber) {
    if (receivedNumber == 1) {
        robot.setColor(0xff0000)
        wiggle()
        wiggle()
    } else if (receivedNumber == 2) {
        robot.setColor(0x00ff00)
        spin()
    } else if (receivedNumber == 3) {
        robot.setColor(0x0000ff)
        shuffle()
        shuffle()
    }
})
robot.elecfreaksCuteBot.start()
radio.setGroup(1)

Make

Show as code

function wiggle () {
    robot.motorTank(50, -50, 300)
    robot.motorTank(-50, 50, 300)
    robot.motorStop()
}
function spin () {
    robot.motorTank(50, -50, 1200)
    robot.motorStop()
}
function zigzag () {
    robot.motorTank(50, 20, 500)
    robot.motorTank(20, 50, 500)
    robot.motorStop()
}
function phraseA () {
    radio.sendNumber(1)
    music.play(music.stringPlayable("E D C D E E E - ", 120), music.PlaybackMode.UntilDone)
}
function phraseB () {
    radio.sendNumber(2)
    music.play(music.stringPlayable("D D D - E G G - ", 120), music.PlaybackMode.UntilDone)
}
function phraseC () {
    radio.sendNumber(3)
    music.play(music.stringPlayable("E D C D E E E E ", 120), music.PlaybackMode.UntilDone)
}
input.onButtonPressed(Button.AB, function () {
    phraseA()
    phraseB()
    phraseC()
})
radio.onReceivedNumber(function (receivedNumber) {
    if (receivedNumber == 1) {
        wiggle()
        wiggle()
    } else if (receivedNumber == 2) {
        zigzag()
    } else if (receivedNumber == 3) {
        spin()
    }
})
robot.elecfreaksCuteBot.start()
radio.setGroup(1)

Stretch and support

Stretch: Give each robot its own part: robots with a role variable (lead or backup) do different moves for the same cue.

Support: Give phraseC complete; students add the dancer's branch and the new move.

Exit ticket

Why does each phrase play its music until done before the next phrase starts?

So the next cue is only sent when the music reaches the next phrase. The robots then move in time with the tune.

What each step is for

Investigate: A cue is sent at the moment a phrase starts, and the robot acts when it arrives. Playing each phrase until done is what spaces the cues out in time.
Modify: Each new part of the show is a phrase with its own cue on the conductor, and a branch with its own move on the dancers.

Where it leads

Next: the robot talks back, sending an alert to a base station. Real-world links: drone light shows, stage lighting cues, a conductor and an orchestra, synchronised swimming.