About a week ago we invited our friends over for an afternoon tot skool about farms. We played with play dough on an "F" mat. I used a picture of a farm and put the letters Ff in really big font over it. We laminated those sheets and used them to make the letter f out of play dough.
http://www.2teachingmommies.com/p/unit-studies.html to supplement our activities. Which included coloring farm animals (laminated) with dry erase markers.