How many weeks are in April?

I really need to know this;
April is the National Child Abuse Prevention mese (link), and I want to use pictures of Child Abuse victims like Kelsey Briggs and Baby P as my user icona during the whole mese of April. I decided to use one icona of a child during one half a week, and another for the other half. But I need to know exactly how many weeks are there.

Can someone please tell me if they know?

Thanks >333

:)