They are annual killifish so their eggs require a period where they dry out before they hatch.
Of course if you do get them to hatch and survive to adulthood, they usually only live a year, possibly two if you are lucky and experienced (hence the name 'annuals'). So not sure why they would be great fish for kids who would most likely get attached to them.
While they do need a larger aquarium than the advertised bowl, and people who actually have a clue as to what they are doing, many species of killifish can live at room temperature (some actually need a temperature in the 60s to thrive and breed) and keeping them at a lower temperature will extend their natural lifespan.
I keep my three pairs of killifish at around 75 degrees and they have been spawning all morning.