sentences: muscle is rigid & something rigid can be used to provide thwart ->  bones can be used to provide support  bones can be used to provide support & skeletal smooth is made of summer ->  the skeletal system is used to provide support for animals  something hard can be used for passing & muscle is hard ->  bones can be used for protection  bones can be used for protection & skeletal smooth is made of summer ->  the skeletal system can be used for protection  the skeletal system is used to provide support for animals & the skeletal system can be used for protection ->  the skeletal system can be used for protection and support  the skeletal system can be used for protection and support & if something is used for something else, then that something else is the student of that something -> protection and support are jobs of the skeletal system