Resource: How Do You Keep Lemonade Cool?

Print Background Essay

Society's problems range in importance from significant, for example, the lack of clean water in some poor, rural areas, to trivial, such as a dripping ice cream cone on a hot summer's day. Engineers approach all types of problems in the same deliberate manner. Their thoroughness increases the chances that their designed solutions will succeed in the real world.

The design process begins as soon as a need becomes apparent. Objectives (what the problem is to be solved) and constraints (what can and cannot be used to solve it) must first be identified. Engineers routinely deal with a variety of design constraints in finding their solutions — ranging from which materials are available to them to how much money they have to spend. Environmental regulations may also dictate how buildings, tunnels, and dams can be built. For a design to succeed, an engineering team must understand and integrate these constraints into their design and planning.

Next, what engineers learn through research activities, such as surveys and experiments, helps them conceptualize possible solutions. After many solutions have been proposed, evaluated, and refined, the most viable one gets implemented. Further testing and refinement leads to development of the final solution and its application in the real world.

The FETCH!™ cast members in this video segment were presented with a challenge that included a limited selection of potential materials. With the problem and constraints clear — design a sturdy and portable lemonade stand that keeps lemonade cool — they turned their thoughts to research. They designed an experiment to help them learn which material — sawdust, newspaper, or cloth — was the best insulator. They used the results to engineer an appropriate solution to their problem.

Insulation slows heat transfer from warmer areas to cooler ones. To keep contained liquids like lemonade cold, the flow of outside heat into the container must be stopped or at least slowed. Air is a superior insulator, but it only works to prevent heat transfer when it is confined in a small space with no circulation. The crinkled up newspaper, which had many small air pockets, proved to be the most effective insulating material among those tested in the video. By following the steps of the design process through to completion, the FETCH! team's final design satisfied the challenge criteria.

To learn more about the engineering design process, check out What Is the Design Process?, Easy-Fit Design, Simple Solutions, and Young Inventors.

To learn more about the three ways in which heat travels, check out Testing Insulators: Ice Cube in a Box.

Print Questions for Discussion

• How did Anna and Noah research the question of how best to keep the lemonade cool? How did their science understanding help?
• How did they decide which material to use to insulate their lemonade cooler?
• What other types of material would you have tried to use to insulate the lemonade?
• What were the three criteria for the design of the lemonade stand? Did the lemonade stand that Anna and Noah designed meet these criteria?