This activity is a good introduction to photoshop tools. They create a gradient background and then use shapes to create silhouettes. Silhouettes are a useful tool for assessing if a cartoon or illustration reads clearly and is a fantastic way of giving students confidence to draw.
An extension of this activity is combining it with a class activity where all the students print out their landscapes and present them as a long freeze or use Tangram shapes. This is a good opportunity to look at Chinese art, geometry in traditional and decorative art.
As this is a landscape there is an opportunity to explore the 'rule of thirds' and composition.