Cat Bounce Across the Stage — Scratch L1

WHAT IT SHOULD LOOK LIKE

Eight lessons, one animation. This is what you finish and save today — out to the fence, turn, and all the way back, on one green-flag click.

at the start

step 1 of 2

the sprites move as they would on the real Stage

Learning Goals 3 min

By the end of this lesson you will be able to:

Assemble point in direction (90), glide (2) secs to x: (200) y: (0) and if on edge, bounce into one working round trip.
Change a single number and predict how the animation will look before you run it.
Save the finished project as an .sb3 file ready to show.

Warm-Up 7 min

Everything you need already exists in your toolbox. Today is not about learning a new block — it is about the order you put the old ones in.

Where we are now. Four separate skills, all working. The only thing missing is the arrangement that turns them into one animation.

Quick-fire puzzle — find the missing block

This script is one block short. It runs, but the second glide looks wrong. What is missing, and where?


when flag clicked
point in direction (90)
glide (2) secs to x: (200) y: (0)
glide (2) secs to x: (-200) y: (0)

Nearly right. One block is missing between the two glides.

Reveal the answer

It needs if on edge, bounce between the glides. Without it the cat still travels back — a glide always reaches its destination — but it does so still facing right, sliding backwards across the whole garden.

That is the difference between a sprite that moves and a sprite that looks like it means it.

New Concept — assembling a project 15 min

Flour, eggs, butter and sugar are not a cake. What turns them into one is the order and the timing. Your four motion blocks are exactly the same: each is nearly useless alone, and together they make something worth watching.

Every block, and its job today

Block	Category	Its job in this project
`when flag clicked`	Events	Starts everything on one click.
`point in direction (90)`	Motion	Guarantees the cat begins facing right, however the last run ended.
`glide (2) secs to x: (200) y: (0)`	Motion	Carries the cat across the garden slowly enough to watch.
`if on edge, bounce`	Motion	Turns the cat round at each fence. Used twice, once at each end.

The plan, in pictures

WHAT IT SHOULD LOOK LIKE

Out, turn, back, turn. About four seconds from one click — and the cat finishes facing the way it began, ready to go again.

at the start

step 1 of 2

the sprite moves as it would on the real Stage

Why the order is the whole lesson

Each bounce must come after the glide that reaches the edge. Put it before and the cat is still in open garden, the block finds no edge to bounce off, and it quietly does nothing.

Equally, the glide has to actually reach the fence. Aim for 100 instead of 200 and the cat stops short — no edge, no bounce, and the second glide slides it backwards.

Why this is a project lesson

For seven lessons you learned one block at a time. Today you learn something different: how separate pieces become a finished thing. That skill is what turns a pupil who knows blocks into one who can build.

Guided Build — the finished stroll 15 min

Open your Cat Garden Stroll project. We build the animation one leg at a time, testing after each.

WHAT IT SHOULD LOOK LIKE

Stage plan. One sprite, two fences, two legs. The cat is still the only thing you script.

at the start

step 1 of 2

the sprite moves as it would on the real Stage

Step 1 — Hat and heading

Drag in when flag clicked, then point in direction (90). The cat now begins every run facing right, whatever it was doing before.

Step 2 — The first leg

Add glide (1) secs to x: (0) y: (0), then change it to 2 seconds, x 200, y 0. Click the flag: the cat crosses the garden over two seconds and stops near the fence.

Step 3 — The first bounce

Snap if on edge, bounce underneath. Run it again and watch the cat flip to face left as it arrives.


when flag clicked
point in direction (90)
glide (2) secs to x: (200) y: (0)
if on edge, bounce

Half the project. The cat crosses and turns.

Step 4 — The second leg

Add another glide, this one to x −200, again over 2 seconds. Run it: the cat now crosses back — and because it turned first, it walks forward rather than reversing.

Step 5 — The second bounce

Snap a final if on edge, bounce on the bottom. Now the cat finishes facing right again, exactly as it started.

Step 6 — Run it twice in a row

Click the flag, wait for it to finish, then click again. The second run should be identical to the first. That is the real test of a finished project: it does the same thing every time.

Step 7 — Change one number and predict

Before you touch anything, say out loud what will happen if you change both glide times to 0.5. Then do it. Then try 5. The blocks never changed — only the pace of the story.

What changed: eight lessons of separate tricks became one animation that runs itself, repeats reliably, and is worth showing to somebody.

The full assembled stack (your reference)


when flag clicked
point in direction (90)
glide (2) secs to x: (200) y: (0)
if on edge, bounce
glide (2) secs to x: (-200) y: (0)
if on edge, bounce

Six blocks, one click, two bounces, four seconds. Comfortably inside the Level 1 cap of eight.

Try It Yourself — extend the project 12 min

🟢 Easy

Goal: Give the cat something to say at the far fence, so the turn feels deliberate rather than accidental.

WHAT IT SHOULD LOOK LIKE

The bubble belongs at the turning point — after the bounce, before the return leg.

at the start

step 1 of 2

the sprite moves as it would on the real Stage


when flag clicked
point in direction (90)
glide (2) secs to x: (200) y: (0)
if on edge, bounce
say [Bounce!] for (1) seconds
glide (2) secs to x: (-200) y: (0)
if on edge, bounce

Think: seven blocks now, and the run takes a second longer. Say blocks hold up the script while the bubble shows, which is why the pause lands exactly where you put the block.

🟡 Medium

Goal: Turn the dash into a lazy Sunday stroll. Change nothing but the timing, and watch how different the same journey feels.

WHAT IT SHOULD LOOK LIKE

Same six blocks, same distance — ten seconds instead of four.

at the start

step 1 of 2

the sprite moves as it would on the real Stage


when flag clicked
point in direction (90)
glide (5) secs to x: (200) y: (0)
if on edge, bounce
glide (5) secs to x: (-200) y: (0)
if on edge, bounce

Think: try 1 second each way as well. Which pace suits a cat in a garden? There is no single right answer, and choosing is part of animating.

🔴 Stretch

Mini-mission: bounce the other way. Rebuild the whole round trip so the cat travels up and down between the top and bottom fences instead of side to side.

WHAT IT SHOULD LOOK LIKE

Top fence and bottom fence this time. Every block you need is already in your project.

at the start

step 1 of 2

the sprite moves as it would on the real Stage

It works if: one click sends the cat up to the top edge, turns it, brings it down to the bottom edge and turns it again — finishing pointed the way it began. Stay within 8 blocks.

Think: which heading points at the sky, and which of the two glide numbers has to change? Only one of x and y is doing any work here.

Mini-Challenge — two travellers 5 min

“Passing in the middle”

Add a second sprite to the garden and give it a journey of its own, so the two cross paths somewhere near the middle on the same click.

WHAT IT SHOULD LOOK LIKE

Two sprites, opposite directions, one click. Remember each has its own Script Area.

green flag — both set off

step 1 of 3

the sprites move as they would on the real Stage

It works if:

One flag click starts both sprites at once.
They set off from opposite ends and travel toward each other.
Both turn at their fences rather than getting stuck.
You used only blocks from this lesson and earlier.

Reveal one valid solution (teacher)

The same six blocks on each sprite, with the headings and glide targets swapped. Note these two stacks live on different sprites — they are never in the same Script Area.


when flag clicked
point in direction (90)
glide (2) secs to x: (200) y: (0)
if on edge, bounce
glide (2) secs to x: (-200) y: (0)
if on edge, bounce

when flag clicked
point in direction (-90)
glide (2) secs to x: (-200) y: (0)
if on edge, bounce
glide (2) secs to x: (200) y: (0)
if on edge, bounce

The classic mistake is building both stacks on the cat. The cat then does two round trips in a row and the butterfly never moves — a good reminder of Lesson 5.

🚀 Mission — Polish and ship it

WHAT IT SHOULD LOOK LIKE

The whole arc, finished and packed into one file you can carry anywhere.

at the start

step 1 of 2

the sprite moves as it would on the real Stage

Your animation works. Now make it feel finished, and get it out of the browser.

Add one flourish. Something small that makes the run feel deliberate — a line as the cat sets off, a reaction at a fence, a celebration at the end. One is plenty.
Check it repeats. Run it three times. All three should look the same. If they do not, something is missing from the top of your stack.
Name it and save it. Give the project a real name, then File → Save to your computer.
Prove it survived. Close the tab, reopen Scratch, load the file, and run it once more.
Share it (optional). With a scratch.mit.edu account you can click Share and bring a link instead. Under-13s need a parent’s email; the file works just as well.

✅ Done when: your saved file reopens and runs the full round trip with your flourish intact. Going further: add the second traveller from the mini-challenge before you save.

Recap 2 min

Today you assembled the whole motion cluster into one animation. A hat to start it, a heading so it always begins the same way, glides to carry the cat at a watchable pace, and a bounce at each fence to turn it round. Six blocks, one click, a complete round trip — and the ordering was the entire difficulty.

Project: A complete artefact you can run and show, built by combining blocks you already know.
Round trip: A there-and-back journey. Here: glide, bounce, glide, bounce — finishing where it began.
Arc: A run of lessons building one shared project. This one ran eight lessons and ends today.

Homework 1 min

Faster, slower, higher. Take the finished project and change two numbers, then explain what you saw.

WHAT IT SHOULD LOOK LIKE

The same round trip, raised into the upper half of the garden — but still comfortably below the top fence.

at the start

step 1 of 2

the sprite moves as it would on the real Stage

Open your saved project.
Change both glide times. Try 0.5 for a dash, or 4 for a stroll.
Change both glide y values from 0 to 120, so the trip runs along the top half of the garden.
Click the flag and watch. Screenshot your Script Area.

Bring back next class:

A screenshot of your modified six-block Script Area.
Your answer to: “At y = 120 the cat still bounces off the left and right fences, but never off the top. Why not?”

Heads up for next class: SCR-L01-15 opens a new arc — 💃 Cat Dance Party. It starts by looking properly at the green-flag hat you have been using since Lesson 1, then adds new ways to start a script.

WHAT IT SHOULD LOOK LIKE

Eight lessons, one animation. This is what you finish and save today — out to the fence, turn, and all the way back, on one green-flag click.

at the start

step 1 of 2

the sprites move as they would on the real Stage

Learning Goals 3 min

By the end of this lesson you will be able to:

Assemble point in direction (90), glide (2) secs to x: (200) y: (0) and if on edge, bounce into one working round trip.
Change a single number and predict how the animation will look before you run it.
Save the finished project as an .sb3 file ready to show.

Warm-Up 7 min

Everything you need already exists in your toolbox. Today is not about learning a new block — it is about the order you put the old ones in.

Where we are now. Four separate skills, all working. The only thing missing is the arrangement that turns them into one animation.

Quick-fire puzzle — find the missing block

This script is one block short. It runs, but the second glide looks wrong. What is missing, and where?


when flag clicked
point in direction (90)
glide (2) secs to x: (200) y: (0)
glide (2) secs to x: (-200) y: (0)

Nearly right. One block is missing between the two glides.

Reveal the answer

That is the difference between a sprite that moves and a sprite that looks like it means it.

New Concept — assembling a project 15 min

Every block, and its job today

Block	Category	Its job in this project
`when flag clicked`	Events	Starts everything on one click.
`point in direction (90)`	Motion	Guarantees the cat begins facing right, however the last run ended.
`glide (2) secs to x: (200) y: (0)`	Motion	Carries the cat across the garden slowly enough to watch.
`if on edge, bounce`	Motion	Turns the cat round at each fence. Used twice, once at each end.

The plan, in pictures

WHAT IT SHOULD LOOK LIKE

Out, turn, back, turn. About four seconds from one click — and the cat finishes facing the way it began, ready to go again.

at the start

step 1 of 2

the sprite moves as it would on the real Stage

Why the order is the whole lesson

Each bounce must come after the glide that reaches the edge. Put it before and the cat is still in open garden, the block finds no edge to bounce off, and it quietly does nothing.

Equally, the glide has to actually reach the fence. Aim for 100 instead of 200 and the cat stops short — no edge, no bounce, and the second glide slides it backwards.

Why this is a project lesson

Guided Build — the finished stroll 15 min

Open your Cat Garden Stroll project. We build the animation one leg at a time, testing after each.

WHAT IT SHOULD LOOK LIKE

Stage plan. One sprite, two fences, two legs. The cat is still the only thing you script.

at the start

step 1 of 2

the sprite moves as it would on the real Stage

Step 1 — Hat and heading

Drag in when flag clicked, then point in direction (90). The cat now begins every run facing right, whatever it was doing before.

Step 2 — The first leg

Add glide (1) secs to x: (0) y: (0), then change it to 2 seconds, x 200, y 0. Click the flag: the cat crosses the garden over two seconds and stops near the fence.

Step 3 — The first bounce

Snap if on edge, bounce underneath. Run it again and watch the cat flip to face left as it arrives.


when flag clicked
point in direction (90)
glide (2) secs to x: (200) y: (0)
if on edge, bounce

Half the project. The cat crosses and turns.

Step 4 — The second leg

Add another glide, this one to x −200, again over 2 seconds. Run it: the cat now crosses back — and because it turned first, it walks forward rather than reversing.

Step 5 — The second bounce

Snap a final if on edge, bounce on the bottom. Now the cat finishes facing right again, exactly as it started.

Step 6 — Run it twice in a row

Click the flag, wait for it to finish, then click again. The second run should be identical to the first. That is the real test of a finished project: it does the same thing every time.

Step 7 — Change one number and predict

Before you touch anything, say out loud what will happen if you change both glide times to 0.5. Then do it. Then try 5. The blocks never changed — only the pace of the story.

What changed: eight lessons of separate tricks became one animation that runs itself, repeats reliably, and is worth showing to somebody.

The full assembled stack (your reference)


when flag clicked
point in direction (90)
glide (2) secs to x: (200) y: (0)
if on edge, bounce
glide (2) secs to x: (-200) y: (0)
if on edge, bounce

Six blocks, one click, two bounces, four seconds. Comfortably inside the Level 1 cap of eight.

Try It Yourself — extend the project 12 min

🟢 Easy

Goal: Give the cat something to say at the far fence, so the turn feels deliberate rather than accidental.

WHAT IT SHOULD LOOK LIKE

The bubble belongs at the turning point — after the bounce, before the return leg.

at the start

step 1 of 2

the sprite moves as it would on the real Stage


when flag clicked
point in direction (90)
glide (2) secs to x: (200) y: (0)
if on edge, bounce
say [Bounce!] for (1) seconds
glide (2) secs to x: (-200) y: (0)
if on edge, bounce

Think: seven blocks now, and the run takes a second longer. Say blocks hold up the script while the bubble shows, which is why the pause lands exactly where you put the block.

🟡 Medium

Goal: Turn the dash into a lazy Sunday stroll. Change nothing but the timing, and watch how different the same journey feels.

WHAT IT SHOULD LOOK LIKE

Same six blocks, same distance — ten seconds instead of four.

at the start

step 1 of 2

the sprite moves as it would on the real Stage


when flag clicked
point in direction (90)
glide (5) secs to x: (200) y: (0)
if on edge, bounce
glide (5) secs to x: (-200) y: (0)
if on edge, bounce

Think: try 1 second each way as well. Which pace suits a cat in a garden? There is no single right answer, and choosing is part of animating.

🔴 Stretch

Mini-mission: bounce the other way. Rebuild the whole round trip so the cat travels up and down between the top and bottom fences instead of side to side.

WHAT IT SHOULD LOOK LIKE

Top fence and bottom fence this time. Every block you need is already in your project.

at the start

step 1 of 2

the sprite moves as it would on the real Stage

It works if: one click sends the cat up to the top edge, turns it, brings it down to the bottom edge and turns it again — finishing pointed the way it began. Stay within 8 blocks.

Think: which heading points at the sky, and which of the two glide numbers has to change? Only one of x and y is doing any work here.

Mini-Challenge — two travellers 5 min

“Passing in the middle”

Add a second sprite to the garden and give it a journey of its own, so the two cross paths somewhere near the middle on the same click.

WHAT IT SHOULD LOOK LIKE

Two sprites, opposite directions, one click. Remember each has its own Script Area.

green flag — both set off

step 1 of 3

the sprites move as they would on the real Stage

It works if:

One flag click starts both sprites at once.
They set off from opposite ends and travel toward each other.
Both turn at their fences rather than getting stuck.
You used only blocks from this lesson and earlier.

Reveal one valid solution (teacher)

The same six blocks on each sprite, with the headings and glide targets swapped. Note these two stacks live on different sprites — they are never in the same Script Area.


when flag clicked
point in direction (90)
glide (2) secs to x: (200) y: (0)
if on edge, bounce
glide (2) secs to x: (-200) y: (0)
if on edge, bounce

when flag clicked
point in direction (-90)
glide (2) secs to x: (-200) y: (0)
if on edge, bounce
glide (2) secs to x: (200) y: (0)
if on edge, bounce

The classic mistake is building both stacks on the cat. The cat then does two round trips in a row and the butterfly never moves — a good reminder of Lesson 5.

🚀 Mission — Polish and ship it

WHAT IT SHOULD LOOK LIKE

The whole arc, finished and packed into one file you can carry anywhere.

at the start

step 1 of 2

the sprite moves as it would on the real Stage

Your animation works. Now make it feel finished, and get it out of the browser.

Add one flourish. Something small that makes the run feel deliberate — a line as the cat sets off, a reaction at a fence, a celebration at the end. One is plenty.
Check it repeats. Run it three times. All three should look the same. If they do not, something is missing from the top of your stack.
Name it and save it. Give the project a real name, then File → Save to your computer.
Prove it survived. Close the tab, reopen Scratch, load the file, and run it once more.
Share it (optional). With a scratch.mit.edu account you can click Share and bring a link instead. Under-13s need a parent’s email; the file works just as well.

✅ Done when: your saved file reopens and runs the full round trip with your flourish intact. Going further: add the second traveller from the mini-challenge before you save.

Recap 2 min

Project: A complete artefact you can run and show, built by combining blocks you already know.
Round trip: A there-and-back journey. Here: glide, bounce, glide, bounce — finishing where it began.
Arc: A run of lessons building one shared project. This one ran eight lessons and ends today.

Homework 1 min

Faster, slower, higher. Take the finished project and change two numbers, then explain what you saw.

WHAT IT SHOULD LOOK LIKE

The same round trip, raised into the upper half of the garden — but still comfortably below the top fence.

at the start

step 1 of 2

the sprite moves as it would on the real Stage

Open your saved project.
Change both glide times. Try 0.5 for a dash, or 4 for a stroll.
Change both glide y values from 0 to 120, so the trip runs along the top half of the garden.
Click the flag and watch. Screenshot your Script Area.

Bring back next class:

A screenshot of your modified six-block Script Area.
Your answer to: “At y = 120 the cat still bounces off the left and right fences, but never off the top. Why not?”