Little Mouse, Little Mouse that could be adapted to feature any animal that starts with the letter of the day, I made up this set of doors and a simple chant:
We're looking for an animal that starts with ["P"]
and we won't stop 'til we find it!
Now, let's give the [RED] door three sharp knocks
and see who hides behind it!
KNOCK! KNOCK! KNOCK!
The doors (and animals) are laminated cardstock with magnets on the back--I use a 13 x 13 black magnet board I picked up during back-to-school-magnet-boards-everywhere season (I glued black felt on the back, so this portable board can double as a small flannel board). Size reference: two doors fit on an 8 x 11" page in landscape orientation.
When an animal's revealed, I ask what kind of animal it is. "That's right; it's a koala! K-k-koala: does 'koala' start with 'P'? No? Okay, which door should we knock on next?"
When possible, I try to use slightly less "obvious" animals--a leopard instead of a lion, a hedgehog instead of a horse--to build vocabulary. Once you've made a set of doors, lots of variations are possible (For ex, "We're looking for a JOB that starts with 'P'" with images of different workers. "What's her job? That's right; she's a veterinarian. Does 'veterinarian' start with 'P'?")
Here's a .pdf of the doors if you'd like to reuse them. Most found via Google Image Search under free to use and modify, but I can't guarantee all of them (or remember which, if any, weren't).