User request: "unit square" to answer field

[oliver-phet]

Please consider explicating “unit square” in the answer field; e.g.:

[ariel-phet]

Considering the way that "area" is defined for the sim on the explore screen (and from the feedback in the game), I don't think there is any confusion about this issue for most users. Plus this change would create a serious i18n headache.

That being said, deferring to @amanda-phet to make a decision whether to act on such feedback

[amanda-phet]

If we added units here we'd obviously want to do that on the Explore screen as well, including the value for perimeter. I'm not sure i18n would be an issue because the units could be named just below the readout (between the readout and the 7-8-9 keys). However

I see where this user was coming from, but leaving out units also allows teachers the flexibility to say a side is 1 ft, 1 in, 1 cm, etc.. Since this sim does not cover learning goals about units, I don't feel like this is essential, but if it doesn't actually cause a headache I'd like to keep this issue open for down the road if this sim gets worked on again.