Toy makers are changing their offerings to appeal to the growing number of dads who are doing more of the family gift shopping, with Barbie construction sets and pastel-hued Legos that experts say appeal to girls and have the potential to help them learn spatial relations and improve math and science skills. “Once it’s in the home, dads would very much be able to join in this play that otherwise they might feel is not their territory,” said psychologist and Mattel consultant Maureen O’Brien.