Lesson Summary Students look closely at joints in their bodies and categorize them by similarities of operation.  Joints in the human body are compared to mechanical devices such as hinges and ball-and socket connectors. Teacher Background The human skeleton has three basic types of joints: hinge, ball-and –socket, and gliding joints.  These joints allow the body to move in many different ways. Set-up/Management Tips Make sure all materials are out and ready for the activity. Locate materials for joint models in the kit. Have response sheet ready for assessment at the end of activity. Copy any journal sheets needed for this activity. Literacy Support Books Available Through VAST Mediagraphies: (see Literacy Links) Science Stories Comparing Joints Scientific Vocabulary The following words are key vocabulary words that will be introduced in this lesson and reinforced throughout the unit: compensate ball-and-socket Joint hinge joint gliding joint