This week I learned about communication, radios and how they each work. The smoke signal is a way that people used to communicate long ago. They would make fire and cover and uncover the smoke in patterns to communicate. Then, there was the pony express which was used from 1860-1861 it only lasted about 18 months. They would ride horses from St. Joseph, Missouri to Sacramento, California. They would stop every 10 miles at swing stations to change out their tired horse for a fresh one since they carried 20 lbs of mail and 20 lbs of protection they must weigh under 125 pounds because all of that weight is the limit that horses can carry. Electromagnetic radiation is energy charged and uncharged fields. Radio propagation is alternating the power of a current. A radio is a device that can control electrons. Two types of radios are catching radios which only catch radio waves. The other kind of radio is a 2 way radio which catches radio waves but also can give radio waves.