Think of Monday's NYT's Connections puzzle as a lowkey apology from editor Wyna Liu.
Why it matters: Yes, a mole can be a unit, and yes, that explains why many players were aggrieved on Saturday.
How it works: Players of Connections have to find a theme that links four words. On Monday, the hardest (purple) grouping was <ANIMAL, BIRTHMARK, SPY, UNIT>.
The given Connection: "What a mole can be."
Between the lines: On Saturday, some players started off by attempting <FOOT, MOLE, KELVIN, METER> on the grounds that they are all units.
That answer was wrong, and generated an embarrassing 🟩🟨🟪🟩.
"Units" wasn't one of the four groupings at all.
The big picture: Connections rarely if ever has a grouping that clear and unambiguous that's also wrong. So when puzzlers woke up on Monday to see the editor say explicitly that a mole can be a unit, they were a little bit vindicated.
Fun fact: A mole is is a unit of quantity. A mole of salt contains 602 sextillion salt molecules, while a mole of water contains the same number of water molecules. (That's about 18 grams, or 0.6 fluid ounces.)
The bottom line: A lot of folks learned about Avogadro's constant this week.