Planning Investigations That Work

By the end of this lesson, you will be able to choose and plan the right kind of investigation to answer a question, and use engineering steps to design a solution to a problem.

Scientists do not all work the same way, because not all questions are the same. In a descriptive investigation, you observe and record information about something without changing anything, like listing every kind of insect you find on a school fence. In a comparative investigation, you collect data on two or more things and compare them, like measuring how tall the grass grows in a sunny corner of the field versus a shady corner. In an experimental investigation, you purposely change one factor, keep everything else the same, and measure what happens, which lets you test cause and effect.

Picture a Texas football field in August. You notice water bottles left in the sun get hot fast. A descriptive study would be recording bottle temperatures throughout the day. A comparative study would be checking bottles left in the bleachers, the shade, and a cooler. An experimental study would be wrapping some bottles in foil, leaving others bare, keeping the size, starting temperature, and location the same, and then measuring temperatures after thirty minutes.

Engineering starts from a problem instead of a question. If players keep drinking warm water, you could design an insulated bottle sleeve from cardboard, cloth, or foam. You build a model, test it against a set goal such as keeping water below eighty degrees for an hour, then improve the weakest part and test again.

No matter which path you choose, plan before you start. Write your question, list your materials, decide what you will measure and how often, repeat trials so one odd result does not fool you, and follow safety rules like wearing goggles and reporting spills.

Try it: If you want to know whether shade slows how fast ice melts, which type of investigation should you plan?