Ostracon is the word that archaeologists use for the flakes of limestone that Ancient Egyptians used as notepads.  A clean, fresh break in the limestone from the hills of Western Thebes often exhibits a flat surface ideal for writing out lists, making notes, and for sketching. 

This particular piece was used on both sides.  On the recto, shown here, a preliminary sketch shows a man facing right, carrying two incense stands as offerings. There is no colour, and no detail in his face, clothing, or the offerings.  On the verso is an incomplete sketch of a man, now showing only the lower legs. Images of offering bearers are very common in the tombs built into the hills around Deir el Bahari.  The crudeness of this sketch suggests it was the copying of an apprentice.