Black holes are nature's giant vacuum cleaners in space. Once something falls into it, there is no escape - no going back. Even light cannot escape. Hence, black holes cannot be seen. The purpose of this activity is to understand why light cannot escape.
The activity has four student pages and two cream colored solution pages for the teacher.
Since an atom is made up of mostly empty space, the activity imagines that we can shrink our Earth in stages to get rid of some of that empty space. In stages students calculate the escape speed for a rocket, what a 200 lb man would way and what a one pound weight would be when the Earth was shrunk to the following diameters: 8,000 miles, 2,000 miles, 160 miles, and finally 2 inches. The final calculation shows that for a rocket to escape it would take a speed of 112 million miles per second. Since light does not travel that fast, light also would be trapped.