Exploring Snap! Code

Exploring Snap! Code

Share one computer. Take turns typing and reading.
Snap! is a computer programming language. Programs are sets of instructions (called scripts) that tell the computer what to do. Since Snap! is a visual language, you will build your programs by dragging blocks (individual instructions) and snapping them together into scripts.

1. Bookmark or write down the Snap! link. You will need it every day.
   Use the URL http://snap.berkeley.edu/run to launch Snap! in a new window (or tab).
2. Build this script. There are instructions below. Then click on the script to see what it does.
   
   
Building a Script   (Yellow boxes are optional reading.) 
This animation shows how to build the script. Drag one block underneath another to snap them together. The white bar shows where the block will snap.

Instructions
The blocks' colors match their palettes: blue for Motion, green for Pen, yellow for Control, etc.
1. Look through the eight palette categories shown at right to find each of the blocks you need for the script. Drag each block into the scripting area and snap them together.
2. Adjust the numbers to match the script:
   
For You To Do
3. Discuss what this script does and why.
4. Discuss the behavior of the script with another pair. If the results are not the same, check that each script matches the model shown above.

Pair Programming Swap

In this course, you will use a technique that professional programmers call pair programming—writing computer programs in teams of two. One partner writes the program; the other partner helps plan and helps catch errors.
Switch roles often, aiming for equal time in each role. If you haven't swapped yet, swap now.

Reference for the script that draws a square:

5. Experiment! What happens if you...
   1. Change the number in the block and click the script to run it again?
   2. Change the number in the block and run the script again?
   3. Change the number in the loop?
   4. Click the block in the green Pen palette?
You can click (or any other block) in its palette or in the scripting area to run it at any time.
If you click a block that is part of a script, the whole script will run.
6. Look back at the code that drew a square. Discuss how each block contibutes to the overall behavior.

1. Experiment more! Create a program that draws something. Below are other blocks that you may find useful. Find them by their color coding, and click on them to see what they do.
   
If you see some feature or code that you like, build something like it in your own program.
2. with another pair. Discuss how each block contibutes to the overall behavior.