What are variables and how (and why) should I use them?
I got home last night, and the cat insisted he had not been fed all day, and was STARVING. I hadn't been there all day, so I didn't know, and my wife was off to her quilting party, so I couldn't ask her. Fortunately, she left a sticky note on the counter that said "I fed the cat", so I knew not to feed him again.
The note she left me is the variable. I couldn't see her feed the cat, but I could see the note and know what went on while I was gone. Storyline is just like I was. One slide has no way of knowing what happens on another slide, but it can read a message left for it in a variable, and know what the learner did on another slide, provided you, the developer, used those actions on that other slide to change the contents of a variable.
The cat got pretty insistent, so I gave him a snack, crossed out her message, and wrote, "He's also had a bedtime snack", and went to my meeting.
The note is the variable. Everybody can see it, and it never changes unless you, the developer, create a trigger to change it.
My wife is getting older (I'm not, just she), and takes a bunch of medicines. She puts them in one of those little plastic gadgets with seven boxes. Every night, (if she remembers :) ) she looks in the box for that day. If it is empty, she knows she has taken her pills that day.
The pill box is the variable. She can't always remember everything, but if the box has pills in it, she knows to take them.
Variables are designed to be seen everywhere, but not heard (much like small children of a previous generation). SL cannot multi-task, so only one slide at a time can be active. SL has no memory, so when a slide becomes active, it can't know what went on while it was hibernating. That's why variables were invented. Each slide can look at the note (variable) and by seeing what is on there now, it can know what went on somewhere else, or some other time. I couldn't hear my wife write the note, but I can read it and know what went on at home while I was not there.
Variable aren't actual things, nor parts of your project, just like the pillbox isn't part of my wife's medicine. They are just post-it notes to carry information from one part of the project to another, and are most useful in trigger conditions.
