Learning Computation Layer in Desmos: Day 1

I've decided to document my learning, questions, notes, neuron-firings...and my poor ol' neglected blog seems to be as good a place as any to do that. I'll use italics when I think I've answered my own question. I want to make clear that all this is in no way meant as a critique of the Desmos team's writing or teaching abilities - both are epic. I'm expressing the thoughts/reactions/difficulties I'm having as I work through it all, in case I am not alone, and in case there's someone out there who can untangle this for me.

Day 1:

I've read this before, not sure why I think this time will be different and suddenly all will be clear, but here goes.

First words that I get snagged on "Sinks are the data that you set for a component. The text label on an action button. A variable in a graph. The text a student sees in a note." "set for a component" means inject into a component so that component now contains that value? The example with the slope and the graph confirms that to be the case.

Next snag: "graph and math input" this terminology seems important but it is sort of appearing out of nowhere. I'm inferring from the example that a math input is a number? Ohh input refers to the type of component, nothing to do with CL, it's just one of the options you can put on a screen when you make any Desmos activity? I straight up did not get that any of the other times I read this. Holy crap.

"Next we'll need..........exp1" good, clear, I expected that the source needs to have a sink. But then "To add a CL script" where did "script" come from? (answered later) And "preset options"? I believe preset options are the set of possible data types for a given type of component. Eg in an input component, if the f(x)math option is selected, the data type must be number or latex, and if text is selected, the data type has to be content.

The "Try It" is great, and it also shows the actual activity screens where we can look into the gearbox. I'd like to have Try Its for my kids somehow somewhere about something. Now I see that the input, which is the source, only needed to be given a name, but the graph, which is the sink, needed more - it needed what I'm guessing is the script, or instructions, which look like this: number("m"): exp1.numericValue .   (There's that syntax that confounds me but I know this is just an intro example)

"Data types" "strings" more new vocab. Starting with 3 simple data types number, string, and boolean, and my question about strings is answered.

"General syntax" - deep breaths.

Sinks are always followed by a ":" "For example, the "content" sink of a note lets you define what the note says"  and I am snagged. Don't know what content sink is. But at least I now know that note is the same as the note component in a Desmos activity.

content: "Hello! I'm the computation layer!" so the colon after the word content means that this component is being defined as a sink? Yes! In other words, something whose content is coming from somewhere else? Not really, it's coming from what's between the quotation marks. Also I notice the "overriding whatever's already there" - that's important to note but then why would anyone even type anything in the original note if it's not going to show up because of the CL? Because only the teacher would see what typed in the original note, and that might be a note to self type of thing. Also not sure why this is a sink. I got why the graph in the previous example was a sink, something in it was coming from another component, which was the source. But what other component is the source for this sink? There isn't in this case, because what's being injected into the note is what's between the quotation marks. It's functionally equivalent to just typing "Hello...layer!" into the note And I don't know why the word "content" is even there. Because that's the data type for this sink.

"Some sinks take a single parameter as an argument" new vocab again. I mean I know what argument and parameter mean in math but not here. They mean pretty much the same thing here.

number("m"): 1.5

number("b"): 2

I see the colons which mean that these components are sinks. But suddenly there are brackets and quotation marks, which I'm sure will be explained later, but I'm starting to feel like I'm getting lost again. And there isn't a source component for which this is the sink? The source is just the numbers 1.5 and 2? Yup. In this case, m will always only be 1.5 and b will be 2. Functionally equivalent to typing y = 1.5x + 2 in the graph.

Variables: I do not understand this at all. Oh. In the Try It script I replaced "hello world" with "wut up" and that's what was displayed in the preview! So the script content: greeting means that whatever the content of the variable "greeting" is will be displayed in the note.

"You can reference variables defined....using the script keyword" I did the same experiment, changed hello world to wut up on screen 3 then the preview for this screen, screen 4 showed wut up. 

content: note3.script.greeting the : means this component is a sink, script means I guess use the script that accompanies the variable greeting. What is the "note3" for tho? I don't see anything - wait it's on screen 3, that's the name of the note on screen 3. But why is it here in this script and doesn't this make note3 a source? It does. Not sure what my confusion was about here.

Sources: : "Each component has a different set of sources" - has or could have? Does this have anything to do with data types? Yes. 
"expression input" new vocab. "We can read things off all its sources" now it sounds like they really meant "has" and not "could have".

Been at this for about 1.5 hours. Back to vacation hours.