1. Intro to CS Monday, August 29

2. Today’s Objectives Review SNAP! one more time Explore More Blocks
If/Else
Repeat
Forever
Broadcast
Ask/Answer
Boolean (and, or, not)
Global and Local

3. SNAP! User’s Manual http://snap.berkeley.edu/SnapManual.pdf
Ch 1. Blocks, Scripts, Sprites
Ch 2. Saving and Loading projects
Ch 3. Building a Block
Ch 4. First Class Lists
Ch 5. Typed Inputs
Ch 6. Procedures as Data
Ch 7. Object Oriented Programming
Ch 8. The Outside World
Ch 9. Continuations
Ch 10. User Interface Elements
Index

4. The Actors in the “Play”
The Stage
Actor 1 (Sprite 1)
Actor 2 (Sprite 2)
Actor 3 (Sprite 3)
Scenery
Script 2
Script 3
Script 1
Costume 1

6. Customizing a Costume

7. Example: Find a Mario costume
First, find one you like. One way is to search for “mario” in Google Images. Then drag the one you like to your desktop.

8. Example: Find a Mario costume
Then, import it as a costume for one of your Sprites by dragging it from your desktop.

9. Exercise 1: Add, remove and reposition sprites
Find an image that you would like for your Sprite
Add it to your workspace as a Sprite “costume”
Replace existing costume with your new one
Repeat this process – but only this time draw a STICKMAN Sprite with one leg longer than the other using the graphical editor.

10. What worked? What was difficult?
Lab Exercise 1 Recap:
Discussion
What worked?
What was difficult?

11. Lab Exercise 2: Rotation
Create this simple script, then run it.
Pick your stickfigure figure Sprite with one leg purposely longer than the other
TIMING: 4 mins (total 8Mins)
ACTUAL: 4 min (10 total),
Today, let’s do a deeper dive into the Pen block set.
Who can tell me what these do:
- Pen Up
- Pen Down
- Clear
- Set Pen Color?
- Set Pen Shade
- Stamp
Who can tell me what the following block does?

12. Lab Exercise 2: Rotation
Did any of you get this? Why?
Click each of the three buttons and try it again.
What was different?
What happens with “rotate 180 degrees?”
TIMING: 4 mins (total 8Mins)
ACTUAL: 4 min (10 total),
Today, let’s do a deeper dive into the Pen block set.
Who can tell me what these do:
- Pen Up
- Pen Down
- Clear
- Set Pen Color?
- Set Pen Shade
- Stamp
Who can tell me what the following block does?

13. Did any of you get this? Why?
Lab Exercise 2: Recap
Did any of you get this? Why?
TIMING: 4 mins (total 8Mins)
ACTUAL: 4 min (10 total),
Today, let’s do a deeper dive into the Pen block set.
Who can tell me what these do:
- Pen Up
- Pen Down
- Clear
- Set Pen Color?
- Set Pen Shade
- Stamp
Who can tell me what the following block does?
can rotate
only face left/right
can’t rotate

14. What worked? What was difficult?
Lab Exercise 2 Recap:
Discussion
What worked?
What was difficult?

15. Exploring More Blocks: Variables
What is a GLOBAL VARIABLE?
When would you use a GLOBAL variable instead of a SCRIPT variable?

16. Exploring More Blocks: Broadcast
What does this do?
It puts the scripted value into “message”

17. Exploring More Blocks: Ask and Answer
What does this do?
It puts the value typed by the keyboard into “answer”

18. Question?
What are the differences between
When would you use each?

19. Example of all 3 at once

20. Lab Exercise 3: Variables
There is a problem with this script. Can you find it?
Write your own script that fixes it.

21. What worked? What was difficult?
Lab Exercise 3 Recap:
Discussion
What worked?
What was difficult?

22. Exploring More Blocks: Sensing

23. Exploring More Blocks: Control
These CONTROL blocks control the operation of the SCRIPT. (As opposed to SENSING blocks that control the SPRITE.)
What do they do?

24. Exploring More Blocks: Operators
What is a BOOLEAN OPERATOR?
How do these work?
Conditions that when evaluated result in the answer of “true” or “false.”

25. Exploring More Blocks: Boolean Operators
If BOTH
Condition “A” and Condition “B” are true,
then TRUE
If EITHER
Condition “A” or Condition “B” is true,
then TRUE If
NOT Condition “A”
then TRUE
When you NEST boolean operators, solve inside out

26. AND (both have to be true)
Battery
Switch A Switch B
Switch A closed
Switch B closed?
Lightbulb ON No
Yes
YES!

27. OR (either one has to be true)
Battery
Switch A
Switch B
Switch A closed
Switch B closed?
Lightbulb ON No
Yes
YES!

28. OR (either one has to be true)
Battery
Switch A
Switch B
Switch A closed
Switch B closed?
Lightbulb ON
NOT Switch B closed? (Switch B NOT closed)
Lightbulb On? No
Yes
YES!
Yes No
YES! No

29. Lab Exercise 4: If/Else & Boolean
Start with your Lab 3 script.
Add a variable that counts the number of times your Sprite has hit an edge. Call it “# WALL HITS.”
If the Sprite hits the wall AND the # wall hits is less than 3, change directions and keep going.
If the Sprite hits the wall, and the # wall hits is 3 or more, then say Game Over and stop.

30. What worked? What was difficult?
Lab Exercise 4 Recap:
Discussion
What worked?
What was difficult?

31. Review: Today Reviewing the SNAP! IDE Costumes More Blocks
Stage, Palette, Blocks, Scripting area, Toolbar
Costumes
Import, Draw, Rotation
More Blocks
Control: forever, repeat, if, if/else, wait
Sensing: ask/answer; broadcast/message
Variable: global, script
Operators: and, or, not

32. Reminders
Read Chapter 2 before the start of class on Wednesday, September 2nd
Quiz – Sept 6nd
Test on Friday, Sept9
on computer parts and SNAP!