Almost every graph you'll meet in real life — in the news, in a report, in an exam paper — comes at you finished, and your job is to pull the numbers back out. Good news: it's exactly rung 2 in reverse.
Reading a Bar Off the Axis
Pick a bar. Run your eye (or your finger) from the top of the bar straight across to the y-axis, and read the number where you land. That's the count for that category. Do it for every bar and you've rebuilt the frequency table the graph was drawn from. If the top of a bar sits between two gridlines, it's halfway between those two numbers — no magic, just careful reading.
A Worked One
A "favourite sport" graph shows footy reaching 8, netball 5, soccer 4 and cricket 3. Trace each across, and the table writes itself: footy 8, netball 5, soccer 4, cricket 3 — 20 students surveyed in all. Now you can answer the real questions: most popular? footy. How many more chose footy than cricket? 8 − 3 = 5. The graph gave you the picture; reading it gave you the numbers to do the maths.
Don't Get Caught by the Axis
Carry rung 3 with you. Before you trust a difference, check where the axis starts — a temperature graph that begins at 18°C will make a mild day and a warm day look worlds apart. Read the actual numbers off the scale, not just the relative heights, and the trick can't get you.
Why This Is the Finish Line
You started by seeing a graph is just a re-drawn table. You learned to draw one, then to dodge the two big traps. Reading a real graph back into numbers — and doing the sums on top — is the whole skill in action. That's mastery, and it's what every "interpret this graph" question is secretly asking.