Most grade and middle schools do not have access to sophisticated video equipment that allows for frame-by-frame viewing. But many schools are starting to have Internet access. Opening an on-line cratering animation from the web page will provide teachers and astronomers with the capability of stepping slowly through the frames, forward or backward or even freezing the frame, to allow the students to visualize what happens before, during, and after impact.
Supplies used in this demonstration are very modest: a 9-inch aluminum pan filled with flour topped off with a thin layer of cocoa powder. At various times, one of three different-sized projectiles, ranging from 0.5 inches to 2 inches is used.
Seven video clips are provided on the demo page. The two clips in each of the first, second and third rows use a small ball bearing, a 1.5 inch diameter rock, a 2 inch diameter rock, respectively, as the projectiles. For each of the three different sized projectiles, there is a wide-field view (on the left) of the impact event and a close-in view (on the right). The seventh clip provides a side view of the demonstration to visualize better the plume that is created on impact. The 2 inch rock was used as the projectile in that instance.
For an excellent web page reference on impact craters and impact crater images, visit:
Note: The referenced demonstrations require QuickTime, which is available for both the Macintosh and Windows platforms.