Just sketching with lead stick. I never used to draw with one of these because I always considered it too soft and broad for the kind of drawing I like to do. It's a Cretacolor Monolith 8B. I used to see art student learning to draw use these because keeps them from concentrating on details and focus on form and structure. Like the kind of drawing exercises that are in Nicolaides The Natural Way to Draw - A book that I would borrow from the library every two weeks from the public library when I was about 14 years old and decided that I wanted to be an artist.
Andrew Loomis was another artist who publish many art instruction books that I learned much from in my teen years. Ken Hultgren was another that I learned a lot from - his speciality was animal drawing.
I always feel like I'm still learning.