There is fun for all ages on a Sunday!
You can find cookie recipes in a lot of cookbooks and books about baking etc so go for it.
The rest of your family will certainly be glad that you created some yummy cookies for them to eat.
Oh, that reminds me; you should bake enough to hide a few for your self for later when they are done.
On a Sunday when the weather is crappy outdoors stay in and bake some cookies. It's fun to do with a younger person, as well.
They learn how to bake, and they really have fun with an older friend or relative at the same time.
Later on you can eat a bunch of cookies and feel real good about the afternoon's fun baking experiment!