Value Square Drawing

I drew eight random drawings in my value scale, going from light values to dark values. I used a regular pencil to make these drawings. I used contrast to make the lines stand out, especially on the last one with the triangles. My project evolved because I shaded in areas that would have been left white, like the second to last drawing where I shaded in gray between the circles. I think I could make it stronger by making the drawings more different form one another. I think that would make this artwork more interesting. I also want to change the white triangles in the last drawing, so that they are darker, that way the whole drawing would look darker.