Each month, thousands of subscribers received a small blue box about the size of a videocassette containing some material such as nylon thread or dinosaur bones.
Some kits would teach about a specific topic, such as coal, static electricity, mechanical linkages, nonwoven fabrics, electroplating, or optical illusions.
[3] Other kits would provide parts to build items such as a small spectrograph, telescope, or pinhole camera.
In addition to the monthly subscription, some kits were available for individual purchase, such as a "soilless gardening" unit which provided seeds, plant food, and instructions in hydroponics.
The instructions were written by Science Service staff, and the kit materials were donated by various companies.