As a commonwealth english speaker for six decades it reads fine to me.
But he loved making things—blocks, pans, ashtrays, anything at all—spin.
And when they span the boy would, as the psychiatrist’s report observed, jump up and down “in ecstasy”.
"And as they spun the boy would .." | "And as they span the boy would .." also parses.
I've never really had any cause to think about this before, but both past tense forms seem natural to me, and I think I use them both. I'm from the UK, if that helps.
I was trying to think of examples when I'd use each one, and it felt to me that I'd use spun if someone spun another object, and span if it was themselves that had been doing the spinning, so e.g. "I span around" (I turned around quickly) vs "I spun the crank" (I caused the crank to spin).
That said, I can also provide counter-examples: "I span the gyroscope" and "I spun around" also both sound completely natural to me, just that I think that I personally would use the other word in both cases.
“Spun” and “span” are both past tense forms of “spin”, but “span” is both archaic and singular, and so would be an odd choice in any current writing, and a disagreement in number where, as here, it is used with a plural subject.
What do you mean singular? I span, you span, he/she/it span, we span, you span, they span. These all sound grammatical to me. I can’t think of many English verbs that inflect differently for the same person but different number. In fact off the top of my head the only one I can think of is “to be” (I am, we were)
There's nothing about it being singular in the dictionary. And I've seen both used in modern writing. Perhaps a US vs UK vs rest of the english speaking world thing?
This seems wrong to me. Past tense of "spin" is "spun".