II.pencil <forma in -ing ecc. pencilling, pencilled brit. angl. penciling, penciled am. angl.>[brit. angl. ˈpɛns(ə)l, ˈpɛnsɪl, am. angl. ˈpɛnsəl]GLAG.preh. glag.
To this end, he developed 14 pencil and paper tasks (known as tools or instruments), with increasing difficulty and which are independent of any content.