Read one or more stories or books that illustrate examples of trustworthiness or the lack of this virtue. For instance, read or tell the well-known folk tale known as "The Boy Who Cried Wolf." Discuss with your class how the presence or absence of trust affected the characters in the story. Talk about the definition of trustworthiness as being the quality of being able to be trusted. Discuss how this is related to being honest even when no one is watching.
Ask your students to write about or draw a picture of one person they trust. Allow the students to present their writing or drawing. Talk about why the people they chose are trustworthy.
Act out simple dramatizations of being trustworthy versus being untrustworthy. Set a scene and invite the students to improvise the action. For instance, you could drop a dollar bill on the floor. Explain that "Anna" dropped the dollar, and "Jack" saw her drop it. Invite a student to play the part of Jack. First advise Jack to do something that is untrustworthy. Then replay the scene and ask Jack to illustrate a trustworthy action. If your students are in upper elementary grades, divide them into groups and have them create their own brief skits about trustworthiness.
Instruct your students to create an action plan for the upcoming week concerning one way in which they can be trustworthy. The students can write the action plan or draw a picture of themselves acting in a trustworthy manner. Revisit the idea the following week and ask for the students to share how they carried out their plans.