Horizontal axis is not labeled.

[pixelzoom]

I just noticed what I believe must be an oversight. The vertical axis is labeled, but the horizontal axis is not. And looking back at 1.0, 1.1, and old dev versions, it's been that way forever -- it is not a regression.

Should we add a label to the horizontal axis?

If so... We do not have room to put a label outside the graph area. And the vertical axis is labeled inside the bounds of the graph area. So perhaps we could put it inside the graph area, just above or below the arrow at the right end of the horizontal axis.

[pixelzoom]

In the design document, screenshots from the original Flash simulation show a label on the horizontal axis - see screenshot below. Mockups for the HTML5 version do not have a label on the horizontal axis - see screenshot below. So either this was an intentional design decision, or it was a design oversight. But I can find no paper trail to support this being an intentional design decision - searching the design document for "label", I find discussion about where to put the label for the vertical axis. But there is no mention of omitting the horizontal axis label.

[catherinecarter]

Thanks for noticing, @pixelzoom. I didn't remember a conversation intentionally leaving the label out, so I asked @amanda-phet if she had a memory. She said:

I don't recall. My guess is space concerns. But showing x or t seems like a good idea.

We could try putting a label where you suggested, @pixelzoom.

[pixelzoom]

OK, will do. I'll start by putting it above the horizontal axis, so that it does not interfere with tick mark labels when the "Values" preferences is turned on.

[pixelzoom]

I'll start by putting it above the horizontal axis, ...

Hmm.... A Google search tells me that the general convention is to put the label below the horizontal axis.

I guess I could center the axis label between ticks 9 and 10 (see screenshot below). But I don't want to turn this into an expensive layout problem.

Or maybe we don't need the tick label at 10? But that might be difficult to omit.

Or I can position the axis label below the tick labels. I think I like that option best.

[pixelzoom]

@catherinecarter This has been implemented and is ready for review. See screenshots below showing layout with and without "Values" preference turned on. Please close if this looks OK.