Sexism??? Gender discrimination? Sexual harassment?

My husband told me about something that happened with his boss today. He works in a head start program as a preschool paraprofessional. He and a female teacher have about 20 preschool students. Today his boss told him (in front of the female teacher) that he shouldn't read to the kids anymore but instead let the female teacher read to them because kids like it better and respond better when a woman reads. I was furious when he told me this because I don't think it is right. Is this okay for her to do? I think it seems like gender discrimination and possible sexual harassment. What should my husband do? Is this okay?