Design the experiment: verify that $F = ma$ using a cart on a low-friction track. Order the steps.

1. Level the track and measure the cart’s mass
2. Apply a known force with a calibrated hanging weight
3. Record position vs. time with the motion sensor
4. Extract acceleration from a fit to the position data
5. Repeat across several forces and plot F against a
6. Check that the plot is a line whose slope equals the mass

The verification is the final plot: if F vs. a is straight with slope m, Newton wins on this track. Notice the architecture, one variable deliberately varied, one measured, everything else clamped. That is experimental design in a single sentence.