Set 24 eggs...due May 4...Any advice for my classroom?

[musicjengel]

I've got a styrofoam incubator that held temperature for 5 days prior to adding eggs.
Egg turner.
good thermometer.
12 Leghorn eggs
12 Rhode Island Red eggs

Waiting for a hygrometer to come in the mail...sigh.

And a small classroom full of kids who are excited to see the chicks hatch.

I've done this twice before. Once very successfully and once not so much because of humidity issues (didn't go up when I locked down).

Any advice?

Thanks!