How does knowing its own history provide a group with a sence of unite

Knowing one's own history provides a group with a sense of unity as it unites them to know how their past brought them together through their past hardships. 

It brings a sense of unity as people can feel they share a history together and have something to relate to, sort of like a nationalistic feeling in a sense.

Therefore, knowing one's history provides a group with a sense of unity as it allows them to feel as though they have something to relate to and have a past that makes them them, in a sense.

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1) clean up you lab area2) dispose of the chemicals as instructed by your teacher3) put everything back where it belongs unless your teacher tells you otherwise4) dispose of gloves5) wash hands with soap and water