Translating data on ACT Science: matching a verbal description of a relationship to its graph, pairing a table with the graph that represents it, and converting between data forms by checking shape and key points.

What this topic is asking

ACT Science explicitly tests the ability to translate data from one form to another: matching a worded description of a relationship to the right graph, or pairing a table with the graph that represents it. The skill is to convert between words, tables, and graphs by checking two things: the overall shape of the relationship and a few key points.

Translate words into shape

A description in words can be converted, phrase by phrase, into the shape of a graph:

• "Increased" or "rose": the line goes up to the right.
• "Decreased" or "fell": the line goes down to the right.
• "Stayed the same" or "constant": the line is flat.
• "Leveled off" or "plateaued": the line flattens after rising or falling.
• "Peaked then declined": the line goes up then down (an inverted U).
• "Faster and faster" (accelerating): the line curves steeper (slope increasing).
• "More and more slowly": the line curves toward flat (slope decreasing).

Reading each phrase as a feature, you build the expected shape and pick the graph that matches it.

Translate a table into a graph

To match a table to its graph, look at how the measured value changes step by step:

1. Compute or eyeball the differences between consecutive values.
2. Equal differences mean a constant slope, so a straight line.
3. Growing differences mean an increasing slope, so an upward curve; shrinking differences mean a flattening curve.
4. Check that the graph's start point, any peak, and end point match the table's first, highest, and last values.

For example, distances of 0, 5, 20, 45 m have growing steps (5, 15, 25), so the graph curves upward, not a straight line. This is the same shape-reading used in reading line graphs and trends, run in reverse.

Check key points, not just shape

Shape gets you most of the way, but key points settle close calls. Confirm that the candidate graph has:

• The right starting value (where the curve begins on the y-axis).
• The right peak or turning point, if the data have one.
• The right ending value.

A graph with the correct overall shape but the wrong starting value or peak is a distractor. Matching a couple of specific points to the table or description rules these out, a check that pairs with reading units and scales in combining figures and reading units.

Try this

Q1. A passage says a quantity "rose quickly at first and then leveled off." Describe the shape of the matching graph. [2 points]

• Cue. A rising curve that is steep at first and flattens later (an increasing line whose slope decreases toward horizontal).

Q2. A table's values increase by 2, then 4, then 8. Is the matching graph a straight line or a curve, and which way does it bend? [2 points]

• Cue. A curve; because the steps grow, the slope increases, so the line curves upward (steeper as it goes).