LESSON 2 Variables in Proportion

Distance vs. Time

When scientists do experiments, they compare variables. They look for simple patterns that will help them better understand the variables and the way they are related. One especially useful pattern is the relationship of proportion. If the ratios of two variables in an experiment are equivalent, the variables are in proportion.

Students did a lab where they investigated the variables distance and time. A student walked at a steady pace and other members of the group measured the time it took the student to travel different distances.

If the walker keeps a steady pace, then the ratios for

are equivalent. For example, if a student walks 3 yards every 2 seconds, then this data table shows the distance traveled ( D ) for several different times ( t ):

Since the student walks at the same speed, the ratios in the table are all equivalent to one another.