Different fields are different. You can get pretty far in engineering fields with FAFO. It doesn't do much in astronomy.

Have you found this sort of interactive graphic helpful in explaining the topic to students? Can you say more?

A small fraction of fission neutrons are emitted later (milliseconds to minutes), and that gives time for thermal expansion and other effects to stabilize the reaction. This was not publicly known in 1940, but is a key enabler for nuclear reactors.

The drama of the story is that the reactors are run subcritical with added neutrons and the operators have to keep them stable on short timelines and it's exhausting, because it'll go prompt critical and explode if you screw up. Real reactors don't have that problem, because...

I am reading Reynolds’ book “fiefs and vassals,” so this is on my mind.

I haven't bothered. The last covid rounds were indistinguishable from any other cold-type infection and it didn't seem worth the hassle.

This was based on a conversation we'd had months before. I am charmed that the child has been quietly thinking about warship design ever since.