Write Your First Computer Game!
Coding: Programming Languages• Just like you can speak Chinese to someone
who understands Chinese to tell them what to do…• A programming language tells a computer what
to do!• During this project, we will learn how to tell a
computer how to make a fun game about a Tadpole and Frog!
Big Ideas
What is Coding?
How Can you Write
Code?What is Scratch?
This is Scratch!
To sign up: Go to http://scratch.mit.edu
and click on Join Scratch
Enter a username and password
Use your Type2Learn username and
password on the label
Enter birth month and year, gender, country and e-mail
Use this e-mail address
Click on Let’s Go!
Click on OK Let’s Go!
Create a New Project
Click on Create
Title your project
Title your project first name + last initial + 1
Scratch: Stage
Stage
Like in real life, the stage is where the performance, or game happens!
Scratch: Sprite
Sprite
Not the soda! An actor or a character that is on the stage, doing what you tell it to do!
Scratch: Script
Scripts
This is where you tell your actor/sprite what to do!
Create Tadpole and Evil Fish
Change the Stage:Choose a background
Code to make Evil Fish move randomly
Code to make Tadpole escape Evil Fish
Make it a gameEnd game when Tadpole gets caught or besomes a frog after 20 seconds of avoiding the evil fish!
Delete the cat sprite
First click on the cut tool
Then click on the cat sprite
Create a SpriteLet’s Get our Hero on Stage!
Click here to find our tadpole!
Create a SpriteHere is our tadpole. On stage, ready to respond to our commands!
The Evil FishNow lets’ get the evil fish on stage!
Choose a sprite from the
library!
The Evil FishNow lets’ get the evil fish on stage!
Choose fish 2. He looks ready
to eat!
Ready for Instructions!Both our actors are on stage. Now we need to tell them what to do!
But first, let’s put them in the water!We need the stage to look like a pond. So let’s do that…
Choose a new backdrop!
But first, let’s put them in the water!Choose “underwater” scene 1, 2, or 3!
Nature Scenes
Our Tadpole and Fish are in Water
Let’s Start by Giving Evil Fish instructions
Click on Evil Fish, so he knows we are telling him what to do.
Click to make him active
Scripts: Instructions to your sprites
There are all sorts of script blocks. These blocks are instructions to tell your sprite what to do. We’ll start with “motion” blocks.
Make sure “motion” is selected
Make Evil Fish Move Forward!
Point at “move” block and DRAG to the script area.
Choose move 10 steps
Nothing Happened!You have to TELL him when to start moving!Click on Events.Drag When [green flag] clicked onto your scripts area.
Choose when green flag is clicked
Move Blocks together to give instructions to your character
Now, the fish will move 10 steps when you click the green flag!
Give it a try!
Slide the blocks together!
Evil Fish Doesn’t Move Very FarEach click of the green flag moves him only 10 steps. Let’s make him keep moving!
Keep pressing the green flag to see Evil Fish move 10
steps
Make Evil Fish Swim ForeverGo to the CONTROL area. These are blocks that let you CONTROL your sprites even more
CONTROL options control what your sprites do
Make Evil Fish Move ForeverA Forever loop tells Evil Fish to do what is inside the loop FOREVER. Till the end of time. And then keep going!
Choose Forever
Make Evil Fish Move ForeverA forever loop tells Evil Fish to move 10 steps FOREVER. Till the end of time.
Give it a try!
Forever loops tell your charater to do what you say
forever and ever
Uh-oh! He disappeared!Evil Fish disappeared. We have to tell him to stay on stage!
If on edge, bounce
Now he’s going only back and forth… lets’ have him turn
Use the turn motion block to tell him to turn
Turn right 15 degrees
Now he’s spinning. Let’s randomize it!
Random: let the computer pick a number!
Let the computer choose a number to turn Evil Fish
Lets do that with the steps too!
This makes it harder to guess where Evil Fish will move next!
Evil Fish is Ready for The Game!
Let’s remember to tell Evil Fish to get on stage to start
the game!
Let’s Save our Progress!
Enter a name for your game
Then click SAVE NOW
Time to Move The Tadpole
First, we need to select the sprite we want to give instructions to.
Click on the tadpole!
Follow The Mouse!For Tadpole to escape the evil fish, we need to make her move by following the mouse pointer around.
Follow The Mouse!For Tadpole to escape the evil fish, we need to make her move by following the mouse pointer around.
Uh-oh. She stopped when he moved once. How do we make her always follow the mouse pointer around?
Follow The Mouse!Now tadpole will follow the mouse pointer forever.
Let’s Make it a Game!
In order for a tadpole to grow into a frog, she needs to be able to avoid evil fish long enough to grow up!
Let’s make it so that Tadpole has to stay away from Evil Fish for 20 seconds to become a frog!
Adding Time to The Game
First, click on your stage.
We are going to now set controls for the whole game, not just our actors/sprites
Adding Time to The GameWhen the flag is clicked, we want to wait 20 seconds then alert the game that the tadpole has won!
From Control
From Sensing
Adding Time to The GameAfter 20 seconds goes by, we need to send off a broadcast, which tells all the actors to pay attention and do something special!
From Events. Choose New Message
Broadcast frog
Adding Time to The GameWhen the actors hear the broadcast frog we need them all to do something!
Tadpole should change into his frog costume.
Evil fish should stop swimming because the game is over!
When 20 seconds has gone by, all the actors will
hear the message frog.
Tell Tadpole She Won!
Click back on Tadpole. Let’s have her respond to the frog broadcast.
Click on Event and choose When I receive . . .
Change this to be frog
Make Tadpole Turn into a Frog!
Tadpole needs to change into her Frog costume
Click on New Costume and choose the Frog costume
Make Tadpole Turn into a Frog!
Choose Frog, click OK
Make Tadpole Turn into a Frog!
Go back to Scripts and Have Tadpole Change costumes when she receives the Frog message!
Check your work! Click the flag. Do you see the timer? Does Tadpole turn into a frog?
Make Evil Fish Stop and Hide!Click back on the Evil Fish so that you can see the script for him.
Click on this last one in the list to tell the other script (the one above that is moving evil fish)
to stop running.
Check your work! Click the flag. Do you see the timer? Does Tadpole turn into a frog?
Wait! Tadpole is still a Frog!We have to go back to the start and have Tadpole get her tadpole costume on!
Tells tadpole actor to start in the tadpole costume
Now . . . if Tadpole swims away for 20 seconds, she turns into a frog!
But wait . . .
What if Evil Fish catches Tadpole???
If Tadpole touches Evil Fish . . .then she loses
An If . . .then looptells a computer: IF something happens, THEN do something
Find this in CONTROL
Let’s put that in code!
Touches the evil fish
Choose evil Fish
Find this in SENSING
If touching evil fish Drag touching
onto the IF until it turns white
Let’s put that in code!
Send a message it’s game over Broadcast!
If Tadpole touches Evil Fish . . .then she loses
Final instructions for tadpole
Tell tadpole what to do if she hears game over!
Tadpole hides!
If Tadpole touches Evil Fish . . .then she loses
But Evil Fish wins!
Tells everyone he won
So if Evil Fish hears GAME OVER…
Tells Evil Fish to stop moving
Final project:
http://scratch.mit.edu/projects/19135697/
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