I think it is crucial that children get exposure to the sad reality, not in order to normalize it but because the idea of hiding it is what stops progress in the first place and confuses children more than the plain truth. Children need truth and not shielding from it. Highly recommended book around this fundamental mistake in education by a French child psychologist: A corps et a cris. Être psychanalyste avec les tout-petits (Caroline Eliacheff).