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The Satellite Delay Relay

Grade Level: 4 - 8

Discussion:

Satellites transmit radio waves from a sender to a receiver and because it takes time for the waves to travel, there is always some delay.

This activity uses the familiar format of the relay race to illustrate the delay between sending and receiving a message via satellite.

Materials:

20 paper cups, divided in half, with each cups in each half numbered 1-10

Procedure:

"On Your Mark" -- Before beginning the relay, choose two students to be ROBOTS and have them wait in another classroom while you explain the rules to the class. Show the remaining students how to build a pyramid with upside down paper cups: 4 for the base; 3 for the second level; 2 for the third level; and 1 for the top. Tell them that this is the "space station" each relay team needs to build. The restriction is that the ASTRONAUT can send only one command per signal to his/her team's ROBOT. For example, a command can be "Pick up cup 1"; as opposed to "Pick up cup 1 and place it next to cup 2." The ROBOT must do exactly what the signal says -- he or she cannot make a move without an order.

Ask the ROBOTS to return to class. Divide the students into 2 groups and choose an ASTRONAUT and SATELLITE for each team. The remaining students are SIGNALS.

"Get Set" -- Remember, no one talks but the ASTRONAUTS-- and SIGNALS during their turns. Put each team's set of numbered cups on desks against the center back wall. Have the ROBOTS stand back-to-back, facing their desks of materials (cups).

Put each team's SATELLITE at the front of the room and facing his/her team's ROBOT. The ASTRONAUTS and line of SIGNALS stand in back corners on their own two sides of the room.

"GO!" -- To race the relay each ASTRONAUT gives a command to his/her SIGNAL who in turn "carries" the command to the team's SATELLITE. After touching the SATELLITE, the SIGNAL delivers the message to the ROBOT who carries out the command. The SIGNAL returns to the end of his/her team's line.

The ASTRONAUT may send the signals as quickly as she/he desires as long as they are sent one at a time. Problems may arise when contradictory signals are received by the robot who as a consequence may not know what to do.

The team that completes the space station first is the winner.

Important Concepts:

(1) In the Satellite Delay Relay a message is carried only several feet. Actual satellites are useful because they can relay information over several thousand miles. Delays occur because it takes time for the radio signals to travel to their destination via satellite.

(2) We can obviously see the SIGNALS in the relay, but actual radio signals are not visible to the human eye.