Introduction to Computer Science with Scratch and App Inventor

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To get a random number, we use the pick random block from the Operators menu. The Operators menu (bright green blocks) contains many mathematical and logical operations and comparisons that will be very useful in programming. To use the pick random block, you specify two numbers and then Scratch will randomly pick a number between those two numbers. Since we want to randomly position our poofs on the stage, we want to randomly pick an x value and a y value to move the poofs to. What should the range of values be for randomly picking an x and randomly pick a y? Remember the coordinate system underlying the stage? The x values on the stage range from -240 to 240 The y values on the stage range from -180 to 180 *HINT* When you are using new blocks in Scratch, remember to notice the shape of the block, this will give you a clue as to where the blocks can be used. If we add a go to x: y: block with our pick random blocks included, our cheesy poofs will show up at a new location every time we start our program over. Give it a try and see how it works. Remember, you still need to stop (click the red stop sign) the program and restart (click the green flag) the program to see the cheesy poofs repositioned on the screen. What would make the game more fun? It would be lots more fun if we didn’t have to restart the program every time we wanted the poofs to reappear. How could we change our program so that every time the dinosaur eats the poofs, they reappear at a new random location on the screen? mbrace Game Development Workbook Page 20
Here is one script that works. To make the poofs reappear each time the dinosaur eats them. Now, let’s add one more thing to our game. Let’s make it harder for the dinosaur to catch the cheesy poofs by making the poofs move around the screen. You already know how to do this – you need a script that moves the poofs around the screen without user interaction like the very first script we wrote for the dinosaur. You can be creative with how you want the poofs to move around the screen – create the behavior you want by using different combinations of blocks from the motion menu. There are all different ways you can make your poofs move around the screen: Use a combination of random, show and hide to make it look like the poofs are falling from the sky Make the poofs move back and forth across the stage Have the poofs bounce randomly around the screen Things to think about when creating poof motion are: Where should your poofs start when the game starts? Do you need to have a specific location? Keep in mind that at the top of the screen, the y axis value is 180 and at the bottom of the screen the y axis value is -180 There is a bounce on edge block that you might find useful Once you have the poofs moving around the screen, you have the start of a fun game! mbrace Game Development Workbook Page 21
Page 1 and 2: Introduction to Computer Science wi
Page 3 and 4: LESSON 1: Getting Started with Scra
Page 5 and 6: I decided to pick a dinosaur. You c
Page 7 and 8: The direction that your sprite move
Page 9 and 10: Let’s add some yellow wait blocks
Page 11 and 12: Changing the Background on the Stag
Page 13 and 14: To use an if block to control the m
Page 15 and 16: Costumes and Animation Now that you
Page 17 and 18: Other useful blocks are the say and
Page 19: ? Now we know how to tell when the
Page 23 and 24: After you create a variable, you wi
Page 25 and 26: Winning, Losing, and Game Play Our
Page 27 and 28: You might have noticed that when th
Page 29 and 30: Click the checkbox next to timer to
Page 31 and 32: Scratch Review Now you have built y
Page 33 and 34: App Inventor Interface The App Inve
Page 35 and 36: The first thing that we will do is
Page 37 and 38: To add the mole to our program, we
Page 39 and 40: Your Blocks Editor Screen should lo
Page 41 and 42: We know that our X and Y locations
Page 43 and 44: Our mole shows up in the emulator,
Page 45 and 46: The last thing we need is the value
Page 47 and 48: Team Project Worksheet We have lear

Introduction to Computer Science with Scratch and App Inventor

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