Expanding just the Grid and not it's content using a storyboard

I'm still very new with Blend and creating a storyboard so please just bare with me, I'm trying to expand a grid using a storyboard, when you click on a button or a picture the grid should then expand, but the problem is that the content inside the grid like the second button I pasted inside the grid is also expanding. Is there someway I can expand the grid without expanding it's content inside. I had this problem with a stack panel, Text box, buttons, frames etc. O and I'm working with a WPf Application and it's XAML