Lesson Summary Students build an arm model with biceps muscles that flexes the arm when it contracts. Teacher Background Muscles contract when they work.  The biceps, like all other muscles, has strong ropelike tissues called tendons at each end.  Tendons attach muscles to bones.  The triceps, located under the humerus, act in opposition to the biceps. Set-up/Management Tips Teacher should prepare model prior to teaching the lesson. Copy any journal sheets needed for this activity. Literacy Support Books Available Through VAST Mediagraphies: (see Literacy Links) Science Stories The Frozen Man Scientific Vocabulary The following words are key vocabulary words that will be introduced in this lesson and reinforced throughout the unit: No new vocabulary.