Learn how digital images are made and how signals are sent and received.

You will need:

• four pieces of graph paper
• a ruler
• two pencils
• a helper

Follow these steps:

1. Choose which person will be the sender (satellite) and which will be the receiver (television). Each person then draws a 10" by 10" square on a piece of graph paper. Draw a grid within the square, so that each small square of the grid is about 1 inch square. This should give you an area with 100 squares in it. The size of the small squares will depend somewhat on the graph paper used - make sure you use some of the lines on the graph paper as guidelines.


2. The sender now draws a simple picture within the 10" x 10" square without letting the receiver see what he or she is drawing.


3. The sender should now “read” the picture to the receiver, using a digital code. If a square on the graph paper is blank, the sender says “Zero”; if the square is filled in or has any mark in it at all, the sender says, “One.” Using this code, the sender starts with the top row and reads from left to right, one square at a time.


4. The receiver, upon hearing this code, transfers the information to his own graph paper. The receiver must mark the graph paper by starting with the top row of squares and going from left to right. If the sender says “zero,” no mark is made. If the sender says “one,” the receiver should fill in the square completely!


5. At the end of the first row, the sender should say, “End row 1,” and repeat this at the end of each row.


6. At the end of the last row, compare the two pictures. Check the results to see how accurate the transfer was.


7. Now, get two more pieces of graph paper and draw 10” by 10” squares on them. This time, your grid size should be close to 1/4 inch rather than one inch. You will have many more squares than before! You can use the same drawing or switch people and the new sender can draw another picture. Follow the same procedure. Describe your results. Compare the accuracy of the two pictures drawn by the receiver. Which one is more precise?

Click on the Activity Button to download the Satellites Assignment.