Here are some ways you can get started...
How do we get a computer cat to take a few steps and say hello?
The Built-in Tutorial
Just click the little question mark inside a new project. It goes over the basics.
These are very useful for learning the fundamentals in a structured and creative way. We have some printed copies on hand...
Write a program that creates interesting patterns or designs...here's an example and a starter kit:
Make an artificial intelligence
This project shows three basic design patterns for making a robot that can talk with you. http://scratch.mit.edu/projects/17455244/
The 10-Block Challenge
Here's some example "first projects" to assign yourself or your students
Build A Maze Game
Something like this can be the foundation of so many types of games. This comes from the new Creative Computing book, which you can download for free here: http://scratched.gse.harvard.edu/guide/files/CreativeComputing20140806.pdf
Create an interactive "about me" project
Another open-ended infinitely expandable idea
Create a "marvelous toy"
It went "zip" when it moved and "bop" when it stopped,
And "whirr" when it stood still.
I never knew just what it was and I guess I never will
In my experience this has been a great project to assign second and third graders, and adults. Kids have high expectations for "games" and don't know what "interactive" is supposed to mean, but a toy that does random stuff is totally appealing to them. Here's one example: http://scratch.mit.edu/projects/22813168/
Some quick-to-build basics to expand on
Feed the Fish!
If Cheese Puffs Then...
Build a Game with Scoring
Offline Version of Scratch: http://scratch.mit.edu/scratch2download
Scratch Cards: http://scratch.mit.edu/help/cards
Scratch Community Guidelines: http://scratch.mit.edu/community_guidelines
Scratch Wiki: http://wiki.scratch.mit.edu
Scratch Discussion Forums: http://scratch.mit.edu/discuss
Scratch FAQ: http://scratch.mit.edu/help/faq
LEGO WeDo Construction Set: http://bit.ly/LEGOWeDo
MaKey MaKey: http://makeymakey.com
Scratch Design Studio List: http://scratch.mit.edu/users/ScratchDesignStudio
Scratch Overview Video: http://vimeo.com/65583694 http://youtu.be/-SjuiawRMU4
Backpack Video Tutorial: http://bit.ly/scratchbackpack
Make a Block Video Tutorial: http://bit.ly/makeablock
Variables Video Tutorial: http://bit.ly/scratchvariables
How can I connect Scratch with other technologies? http://bit.ly/hardwareandextensions
Scratch Chain Reaction Video: http://bit.ly/ScratchChainReaction
Computer Science Concepts in Scratch by Armoni & Ben-Ari (available for download at http://stwww.weizmann.ac.il/g-cs/scratch/scratch_en.html
Seymour Papert's Mindstorms: http://www.amazon.com/Mindstorms-Children-Computers-Powerful-Ideas/dp/0465046746