Once an invention exists, people are likely to think up ways of using it that were never imagined at first. Transportation, communications, nutrition, sanitation, health care, entertainment, and other technologies give large numbers of people today the goods and services that once were luxuries enjoyed only by the wealthy. These benefits are not equally available to everyone. Scientific laws, engineering principles, properties of materials, and construction techniques must be taken into account in designing engineering solutions to problems. Other factors, such as cost, safety, appearance, environmental impact, and what will happen if the solution fails, also must be considered.
Technologies often have drawbacks as well as benefits.
When harm occurs or seems likely, choices have to be made or new solutions found. Because of their ability to invent tools and processes, people have an enormous effect on the lives of other living things. Students explore mirrors to see things that they don't normally see. They investigate mirror images, including reversals and lines of symmetry in geometric shapes and letters of the alphabet. Students explore how to reflect images from one mirror to another.