Programming with Scratch

1. Programming with Scratch Lesson 1: Intro to Programming

2. Computer Programming? • What is programming? • The process of writing, testing, and maintaining the source code of computer programs. • Telling the computer what to do • Why learn to program? • Develops logic and problem-solving skills • Improves attention to detail • It’s fun!

3. But I’m Not a Geek! • Until recently, programming required knowledge of computer language syntax

4. Anyone Can Program! • New tools, like Scratch, allow ANYONE to create computer programs without learning complicated syntax.

5. Programming with Scratch • Open Scratch from either the desktop icon or Start Menu

7. Homework • Download and install Scratch on your home computer • Finish working through the Scratch Getting Started Guide • Feel free to experiment and explore!

8. Programming with Scratch Lesson 2: Scratch Syntax Part 1

9. Statements • In programming, a statement is simply a directive that tells the computer to do something. Think of it as a command or an instruction. • In Scratch, any block whose label reads like a command is a statement.

10. Boolean Expressions • Sometimes, you only want a statement to be executed under certain conditions. Such conditions are defined in terms of Boolean expressions. • In programming, a Boolean expression is an expression that is either true or false. In Scratch, any block shaped like an elongated diamond is a Boolean expression.

11. Boolean Expressions • One such block is: After all, it is either true that the mouse button is down or it is false. • Another such block is: After all, it is either true that some number is less than another number or it is false. • With Boolean expressions can we construct conditions.

12. Conditions • In programming, a condition is something that must be true in order for something to happen. • A condition is thus said to "evaluate to true" or "evaluate to false." • In Scratch, any block whose label says "if," "when," or "until" is a sort of conditional construct.

13. Conditions • If Construct: Instruct a sprite to say hello only if, say, the user has depressed the mouse button: • If-Else Construct: Instruct a sprite to say hello or goodbye, depending on whether the user has depressed the mouse button:

14. Conditions • When Construct: Instruct a sprite to do something when an event occurs: • When Construct: Instruct a sprite to wait to do something until a condition is true:

15. Loops • In programming, a loop can induce multiple executions of statements. • In Scratch, any block whose label begins with "forever" or "repeat" is a looping construct.

16. Follow Me Follow Me applet

17. Homework • Complete the Cat Walk Project • You may wish to use the Scratch Reference Guide as a resource • Completed projects need to submitted by the due date.

18. Programming with Scratch Lesson 3: Scratch Syntax Part 2

19. Variables • In programming, a variable is a placeholder for some value, much like x and y are popular variables in algebra. • In Scratch, variables are represented with blocks shaped like elongated circles, uniquely labeled by you.

20. Threads • In programming, a thread is like a mini-program within a program that can execute at the same time as other threads. • In Scratch, any block whose label begins with "when" essentially demarks the start of a thread.

21. Events • An event is a signal from one thread to another. • Blocks whose labels begin with "broadcast" signal events whereas blocks whose labels begin with "when" handle events.

22. Copter Game Flight Code

23. Copter Game—One Level

24. Adding a Level • Levels can be added using threads and events.

25. Homework • Complete the Your First Game Project • You may wish to use the Copter Game and Levels program as resources. • Completed projects need to submitted by the due date.