Upload
jonathanbyrne
View
844
Download
2
Embed Size (px)
DESCRIPTION
Citation preview
Introduction to Programming
Scratch
Lesson 1
2
Goals
• What is an algorithm?• Scratch Interface• Variables• Conditional Statements • Turtle Graphics• Repetition
3
What is an algorithm?
• A step by step process (Algorithm)– Instructions for making tea (Pseudocode)
If no water in kettle: Put water in kettle
Turn on kettle
While water not boiling in kettle:Wait
Put water in cup …
4
Scratch user interface
5
Scratch stage
6
Stage + Sprite
• Exercise:– Point your mouse to coordinate x=0, y=0
• Exercise:– Get a new sprite on the screen
7
First scratch program
8
Variables
Exercise:Say a random number
Add a variable called “number”
9
Conditions
Exercise:– What does
this code do? – What are the
errors in the code?
10
Conditions
Exercise:– What does
this code do? – What are the
errors in the code?
– What if “number” is equal to 5?
11
Motion statements
• Move Right• Move Left• Big Steps• Small Steps• Move Up• Move Down • Exercise:
Double-click on the blocks to see what happens
12
More motion action
• Exercise– Make the sprite go to x=0, y=0
• Exercise– Make the sprite move 100 steps and turn 90 degrees
• Exercise– Make the sprite go in a square pattern
• Exercise– Make the sprite move when you hit a key
13
Pen statements
• Pen appears underneath sprite
• Pen must be set to “down” before it will draw
• Exercise: Draw a line after the sprite
14
Iteration
• Repeat statements• Exercise:
Guess what this code does
• Test your guess
15
Loop exercises
• Exercise: Draw this (10 diamonds)
• Exercise: Try to write your programs with as few statements as possible
16
More repeating exercises
• Exercise: Draw this in any colour
• Exercise: Change the colour of each square• Exercise: Draw a triangle, a pentagon a hexagon
and a circle.