Presentation on theme: "30 min Scratch July 20091 30 min intro to Scratch A Quick-and-Dirty approach Leaving lots of exploration for the future. (5 hour lesson plan available)"— Presentation transcript:
30 min Scratch July min intro to Scratch A Quick-and-Dirty approach Leaving lots of exploration for the future. (5 hour lesson plan available)
30 min Scratch July Objectives of Scratch unit Intro to visual programming environment Intro to programming with multimedia Story-telling | music-making | game-making Intro to programming concepts objects and attributes sequence, repetition conditions, events, I/O For instructors
30 min Scratch July Secondary objectives Increase student skills with computers Increase student interest in programming Student achievement on fun project Learn Cartesian coordinates, distance computations, etc.
30 min Scratch July Computer scientists Create solutions to problems using computers Study information Invent algorithms Write programs to implement the algorithms Reuse a lot of existing program and machine parts
30 min Scratch July Start scratch and let’s go! Click on the cat icon Or, find “scratch” under “Programs” When home, download from Scratch programming environment comes up quickly
30 min Scratch July Click on the “Looks” button at the top left.
30 min Scratch July Major components At right: the stage with sprite[s] or objects or actors At left: operations and attributes for the sprites Center: scripts or program[s] for the behavior[s] of the sprites Your sprites are actors that you direct with your scripts
30 min Scratch July Let’s implement an algorithm to average two numbers Make a variable “number1” (click and drag and set) Make another one “number2”
30 min Scratch July Compute average first as sum Make variable average Drag a “set operation” to script area Drag a + operation Drag variables number1 and number2 to parameters Click to execute
30 min Scratch July Average script as 4 operation sequence. Change the two numbers and click the sequence to execute the block again.
30 min Scratch July But Scratch computes with multimedia – color, sound, … Can make cartoons Can create stories Can create video games
30 min Scratch July The “hello” script Can do it in 57 languages – java, C++, … Scratch Easy in Scratch: select “Looks” operations and drag the “hello operation” onto your center panel. Then double click on this “lego block”: check your sprite behavior at the right Your very first Scratch program!
30 min Scratch July Make the cat 50% larger 1.Select “Looks” operations 2.Drag the “change size” operator into your script 3.Click and edit for a 50% change (increase) 4.Double click your one operation script 5.Did your cat sprite get 50% bigger?
30 min Scratch July Scripting a sequence of ops Do ops in the following order by dragging operation blocks into a single connected block Say hello Move 200 steps forward Grow 50% bigger Make the “meow sound”
30 min Scratch July Some new operations color change (Looks) wait (Control) move (Motion)
30 min Scratch July Starting a looped script
30 min Scratch July Exercise: write a script to Make the cat move along a square path Say “hi” at all four corners Wait 3 seconds at each corner Change color at all four corners Double size when back to the original starting location. Say “That’s all folks” when done.
30 min Scratch July Elements of Scratch: objects Colors Sounds Locations in 2D space Sprites Costumes Variables (to remember the state of things) Events: that are broadcast for communication
30 min Scratch July Elements of Scratch: control Sequence of operations Loops or repetition Detecting events (key or mouse pressed, sprites overlapping each other, sprites hitting edge of stage, sensor giving value)
30 min Scratch July Loop constructs in Scratch Repeat N times Repeat forever Repeat forever if some condition exists (suppose I’m a sprite wandering about this lab until someone asks a question)
30 min Scratch July Conditions can be checked Do something if sprite k hits sprite m Do something if a certain key is pressed Do something is some variable takes a certain value
30 min Scratch July Interacting with your sprite or story Using mouse Entering a character Asking the user a question
30 min Scratch July Sprite follows the mouse Try changing the number of steps or the wait time.
30 min Scratch July Play and examine MadLib Choose the “file” option at the top of the window Choose “open”, then “examples” Choose “stories” Choose “MadLib” and then read the authors instructions Click OK, wait for load, click green flag
30 min Scratch July About the MadLib story How many actors (sprites)? What is the role of the girl? How are the answers you give 'remembered' and then used in later actions? What is the role of the little whale? What makes the little whale flip around? What makes the big whale spout?
30 min Scratch July Sprites can interact with each other Can detect when colors overlap in space Can detect when sprites bump into edge of the stage See “bouncing balls” example under Simulations under Examples Interact with this simulation Check out the rather complex scripts
30 min Scratch July Check out the break dance Open examples; music and dance; break dance How does break dancing begin? What are the roles of the sprites? What events are in the scripts? What should happen when the boom box is clicked?
30 min Scratch July Experiment with Scratch as time permits Try your own scripts: make moves, sounds, interactions in simple cases Try the examples and learn what makes them work Download Scratch on your own machine and experiment some more Direct a story; or a simulation; or create a video game.