Instead of teaching your child to make the bed, demonstrate how to drape the comforter over a quilt rack. This allows the bedding to breathe during the day, keeping it fresh and sanitary.
Here’s a nice quilt rack that I found on Etsy. It is quite similar to the one my grandmother used!

Remember to put the exterior of the comforter facing downwards, so the interior can air out.
It is particularly dangerous to let humidity build up on conventional mattresses because weirdly toxic molds grow inside them (a predictable response to the chemicals and antimicrobials). In a traditional wool or feather bed, the interior of the mattress can breathe, so it is much healthier.
Remember the silk bedding for your child…
Sweet dreams!