WASHINGTON – Head Start, the federally funded preschool program that serves children and families in low income areas, celebrates its fiftieth anniversary this year.  Hundreds of teachers, administrators and supporters gathered in Washington last week to commemorate this milestone.  Many of those in attendance, including Secretary of Health and Human Services Sylvia Matthews Burwell and newly appointed Head Start national director Blanca Enriquez, expressed concerns about the debate in Congress over whether to slow funding for the program next year.