Britney Spears [1] is one cool mama! On Saturday, the star celebrated the birthdays of her sons [2], Sean Preston and Jayden James Federline, with a trip to Skatelab, a skate park in Simi Valley, CA. Jayden turned 8 on Saturday, and Sean turns 9 on Monday. Britney shared a series of cute snaps and videos on Instagram [3] from the DJ-themed party. In one photo, the family is pictured making funny faces in the car with the caption, "Happy birthday to my boys . . . love you so much Jayden and Preston!" In a short video, Jayden and Sean are seen riding around on IO Hawks [4]. Read on for more of the birthday fun, and then check out Britney's sweetest family moments [5].