This is a nice and easy explanation of using desu. The examples use people to demonstrate X is Y such as, "The man is a lawyer."
The second page of the pdf expands on this to demonstrate X is Y such as, "The shoes are orange." This page has nouns and adjectives. The teacher can have students create their own sentences on a separate sheet of paper or in their notebooks. Students can cut out the words to create their own sentences as well.