I think you have to understand how two things can change "with" each other before you can understand how to read a chart. Personally I think seeing something vary with time or distance is more immediately understandable than reading a chart.
Reading a chart yes, but that's because (IMO) reading is harder than making one. For example, no matter how much someone would explain, I could never understand the relationship between an angle and a sine wave, until I had a teacher made me draw a circle and an x/y axis alongside each other and project the line in the circle onto that axis. I still don't think one can really explain this without resorting to describing what happens visually. But again, maybe that's just me.
