I made this card a few years ago for my best friend's baby shower. It was a very quick card to assemble. The most challenging aspect was finding the perfect clipart of a chalkboard. Luckily I was able to find one that was a vector image. The great thing about vector images, is that you can scale them up or down without losing image quality. So I was able to scale the chalkboard image to the perfect size for my 6"x6" card.
For those of you who are not familiar with the term, a vector image is an illustration composed of lines and curves to form an image, like a WMF or EPS file. This is opposed to a raster image which is made up of pixels, like a JPG file. All photographs are raster images.
Then it was simply a matter of adding the text in Illustrator using an appropriate font (I chose Marker Felt) and printing it out on white cardstock. I then attached the chalkboards to my card base along with some adorable animal stickers and Voilà! My card is complete!
I wonder if my Sister the Math Teacher will object to my skills at addition???
Click to enlarge.