Painting a Value Sketch

Today I was trying to make a value sketch for an acrylic painting of the view out my family room windows. The dogs were hanging around watching. One of them attempted to eat my eraser and one of them kept bumping me with his nose because he wanted something to eat.
Even with the canine "help" I was able to paint a sketch with values of white, light grey, dark grey and almost black. Tonight I hope to paint it...