Pencils are Studiousessences in MySims. You can find them by prospecting in the Junkyard located in the Desert. However, you must begin your prospecting near the entrance to the Junkyard that leads back to the Desert, or you'll receive Stars, Rockets, and Aliens essences instead if you begin your prospecting near the entrance to the Geeky Junkyard Cave. They can also be obtained when Rosalyn randomly drops them. It is used on the monument awarded at 5 stars.