They say that when Dr. Seuss™ The Grinch finally realized what Christmas was all about, his heart grew three sizes that day. Give kids the chance to witness this cardiovascular phenomenon with these fun growing hearts! When left in water for 24 hours, these hearts grow three sizes! Fantastic as classroom Christmas gifts or as holiday party favors, these hearts will delight kids. Foam. (4 dozen per unit) 3 1/2" x 2" cardstock card.