Learning Goals 3 min
By the end of this lesson you will be able to:
- Build the walking T-Rex with its Medium Motor in port A.
- Combine motion, screen text and sound into one short performance.
- Build a rising roar by playing notes from low to high pitch.
Meet the Model — the Tyrannosaurus rex 6 min
What is a T-Rex?
Tyrannosaurus rex was a giant meat-eating dinosaur. It walked on two powerful back legs and had a huge head. Its tiny arms were shorter than a person's.
The science behind it
The T-Rex was a fierce carnivore of the late Cretaceous, about 66 million years ago. Its jaws held banana-sized teeth and could crush bone. Strong hind legs carried its weight, balanced by a long, heavy tail. Its very small arms still had sharp claws.
Where you meet it
You meet the T-Rex in the Jurassic Park films and in roaring animatronic displays. Many museums show towering T-Rex skeletons you can walk right under.
What we'll build
We'll build a stomping T-Rex driven by a Medium Motor on port A. Then we combine the screen, status light and rising notes to make it roar.
Warm-Up 4 min
You can walk a dino and make three kinds of sound. Today you put it all together — the T-Rex's big moment.
Quick-fire puzzle
Ravi runs this. Does the roar get higher or lower?
when program starts :: events hat play beep (40) for (0.2) seconds :: sound play beep (55) for (0.2) seconds :: sound play beep (70) for (0.2) seconds :: sound
Reveal the answer
The roar rises — it gets higher. The note numbers climb 40 → 55 → 70, and higher numbers are higher pitches. Three quick rising notes sound like a growl building to a roar.
New Concept — putting it all together 10 min
Everything you have learned in Level 1 can run in one program: motion, display, status light and sound. A short performance just sequences them in a good order.
Blocks reference (all reused)
| Block | Category | Used here for |
|---|---|---|
[A v] run [clockwise v] for (1) [rotations v] :: motors | Motors | One stomping step. |
play beep (40) for (0.2) seconds :: sound | Sound | One layer of a rising roar. |
write [ROAR] at line (1) :: display | Display | Shows the action on screen. |
set status light to [red v] :: display | Display | Red light for "danger" during the roar. |
Building a roar from notes
A roar is not one note — it is several quick notes that rise in pitch. Stack three or four play beep blocks, each higher than the last, for a growl that builds.
Why it matters
This is how every animatronic dinosaur at a museum works: motors move it while sound and lights play in sequence. You are now sequencing outputs like a real show designer.
Build & Program — the T-Rex 17 min
Part A — Build
Build the walking Tyrannosaurus. One Medium Motor drives the legs through a linkage so it stomps forward.
Components & ports: EV3 Brick · Medium Motor → port A.
- Build the body, tail and short arms; balance it over two legs.
- Attach the legs to a linkage driven by the Medium Motor through gears; plug it into port A.
- Check the head and tail counter-balance so it does not topple.
- Turn the motor by hand to confirm a clean stomping step each rotation.
Part B — Program
Show ROAR, flash a red light, build a rising roar, then stomp forward two steps.
- Start the program and show the word ROAR on screen:
when program starts :: events hat
write [ROAR] at line (1) :: display
- Flash a red danger light:
set status light to [red v] :: display
- Add three rising notes — 40, then 55, then 70:
play beep (40) for (0.2) seconds :: sound
play beep (55) for (0.2) seconds :: sound
play beep (70) for (0.2) seconds :: sound
- Stomp forward two steps:
[A v] run [clockwise v] for (2) [rotations v] :: motors
when program starts :: events hat write [ROAR] at line (1) :: display set status light to [red v] :: display play beep (40) for (0.2) seconds :: sound play beep (55) for (0.2) seconds :: sound play beep (70) for (0.2) seconds :: sound [A v] run [clockwise v] for (2) [rotations v] :: motors
Expected behaviour: the screen shows ROAR, the light turns red, a roar climbs from low to high, and the T-Rex stomps forward two steps — a complete little show.
Try It Yourself — three small builds 11 min
Goal: Make the roar deeper. Lower all three note numbers by 10.
when program starts :: events hat play beep (30) for (0.2) seconds :: sound play beep (45) for (0.2) seconds :: sound play beep (60) for (0.2) seconds :: sound [A v] run [clockwise v] for (2) [rotations v] :: motors
Goal: Stomp first, then roar. Reorder the show so the T-Rex walks in, then roars.
when program starts :: events hat [A v] run [clockwise v] for (2) [rotations v] :: motors play beep (40) for (0.2) seconds :: sound play beep (55) for (0.2) seconds :: sound play beep (70) for (0.2) seconds :: sound
Goal: Siti wants a roar that rises and falls — climb up the notes, then come back down — followed by a stomp.
when program starts :: events hat play beep (40) for (0.2) seconds :: sound play beep (60) for (0.2) seconds :: sound play beep (75) for (0.2) seconds :: sound play beep (60) for (0.2) seconds :: sound play beep (40) for (0.2) seconds :: sound [A v] run [clockwise v] for (2) [rotations v] :: motors
Mini-Challenge — your own dino show 6 min
Combine everything from the Sound cluster. Design a short T-Rex show that uses motion, the screen, the status light and at least two kinds of sound — in any order you like.
It works if:
- The show uses motion and at least two sound types.
- The screen or light gives feedback about what is happening.
- The whole program stays at 8 blocks or fewer.
Recap 2 min
You sequenced motion, display, status light and sound into one performance. A roar is several rising play beep blocks. Ordering your outputs well is what turns separate blocks into a believable show.
- Sequence
- The order blocks run in, top to bottom. Good ordering makes a show feel right.
- Rising roar
- Several notes played in a row, each higher than the last.
Homework 1 min
Name the show. Give your T-Rex performance a title, write it on the screen, then run your show.
Bring back next class: a short video of your show, or a note describing the order of events.
Heads up for next class: EV3-L1-11 builds the Hexapod and uses the Brick's own buttons to start it walking — your first input.