Exercises: The four freedoms

The diagram shows the four freedoms of free software. State them in your own words: what does each one allow you to do? Freedom 3 is marked with «?»: complete it and give an example of how you would exercise each freedom in a school project.

A classmate claims: «free software is software you download for free». Correct the sentence by explaining the difference between free as in freedom and free of charge, and give an example of each case: a program that is free of charge but not free software, and a free software program that is sold.

A teacher downloads a free spreadsheet program, fixes a bug in its code and shares the fixed version with other schools. Identify which freedoms she is exercising in each action and explain which of them would be impossible if the program were proprietary.