Organizing Data With Tables and Graphs

By the end of this lesson, you will be able to organize the numbers you collect in an investigation into a clear table and graph by running repeated trials and finding the mean.

Imagine your class is testing which brand of paper towel soaks up the most spilled water after a Texas thunderstorm blows through the school parking lot. You pour exactly 50 milliliters of water on a tray, lay one towel on it, and measure how much water is left. If you tested each brand only once, a small mistake, like a towel that was folded wrong, could fool you. That is why scientists use repeated trials, which means doing the exact same test several times under the same conditions. Three trials is a common minimum in science class.

Once you have all those numbers, you need a place to put them. A data table is a grid with labeled rows and columns that holds your measurements so nothing gets lost. Your table might have one row for each brand and separate columns for Trial 1, Trial 2, Trial 3, and Average. Always include the unit, such as milliliters, in the column heading.

Next, you calculate the mean, which is the average you get by adding all the trial results together and dividing by the number of trials. The mean smooths out small errors and gives you one fair number to represent each brand.

Finally, you turn those means into a graph so patterns jump out. Use a bar graph when you are comparing separate groups, like paper towel brands, and a line graph when something changes over time, like temperature during a school day. Label both axes, add units, and give the graph a title that says what is being compared.

Try it: If your three trials for one brand gave 30, 34, and 32 milliliters absorbed, what mean would you write in your table?