But if you had a whole classroom of N children soldering, then
N dispersals scattered over the N children might result in a
fume density of N * N / N which would be no dispersal at all!

Industrial soldering set-ups have a small vacuum pipe mounted on
the iron close to the tip to draw away fumes.

"Highland Ham" wrote in message
...
The exposure to fumes by a child will likely be minimal but, as
the purpose will be 'educational', there may be a duty to employ
best practice so they end up knowing what a safe workstation is
like.
Hmm. Depressingly good point. I just hold my breath while soldering
and wash up when I'm done but I really ought to get a hood --
particularly since I'm training my kid to all my bad habits.
With the room being ventilated, a small axial fan positioned close to the
soldering area will adequately disperse the fumes .