Science fair graph maker

How to make a graph for a science fair project

A science fair graph shows the middle number (the mean) of each thing you tried. Put what you changed along the bottom and what you measured up the side, with its unit. The Graph Maker does the adding and dividing for you: tap a box in the table, tap the numbers on the pad, and the mean of each row appears as soon as its tries are in. The graph draws itself as you go, and Peabody says out loud which level was biggest and which way the numbers go. Under the graph the same words are written out, so they print with it.

If you kept a project from Pick my project, its table is ready: the levels, the unit and the number of tries come from the project. Any other project works too: tap how many things you tried, how many tries each, and the unit (cm, inches, seconds, minutes, mm, grams, pennies, times).

Error bars, made simple: the spread of your tries

You do each try more than once because no two tries come out exactly the same. The mean is the middle; the spread is how far apart the tries were. On each bar, or each dot of a line, the Graph Maker draws a thin line from your smallest try to your biggest, with a small cap at each end, and the scale goes high enough to fit your biggest try. Scientists draw lines like these and call them error bars; ours show the range, the simplest kind. A short line means your tries agreed. A long one means something changed between tries, so look for it. When one level's spread is more than half its mean, Peabody says those tries were far apart and suggests trying that level again.

Time it or count it

For a project measured in seconds or minutes, a big Start and Stop timer sits beside the number pad. Tap Start when the try begins and Stop when it ends: the time drops into the box you picked, to a tenth of a second, and the next box is ready. Fingers are a little slow to tap, so have the same person time every try. For things you count, like pennies, drops or swings, tap +1 for each one instead (and −1 if you counted one too many). 18 of Peabody's 118 projects are timed and 43 are counted.

Bar graph or line graph?

Use bars when the things you tried are different kinds, like three floors or three paper towels. Use a line when what you changed is a number that goes up, like 1, 2 and 3 books under a ramp. 38 of Peabody's 118 projects suit a line; the Graph Maker starts on the right one and lets you switch.

What to print for the board

Print your table and graph on one sheet: every try, the means in bold, the graph full width with the spread of each level's tries, the graph in words, and a line for what you noticed. Copy it onto your board in your own handwriting, or glue the sheet on. Your numbers stay on this device and are never sent anywhere. For the rest of the sheets, see the templates, and practise saying what your graph shows with Peabody the judge.