Historiography!

I finally tackle the, "Duck and Cover" video produced in 1951 and shown in classrooms and schools throughout the rest of the decade. These were scary times, and it's important to watch this not as a cynical 2017 inhabitant, but as someone from the 1950's. Why did they make this and why was it important??  https://www.youtube.com/watch?v=IKqXu-5jw60