Follow that? If ants truly gauge the distance they’ve traveled from the nest (and therefore the distance back to the nest) by counting their steps, then returning to the nest with longer legs means they would travel farther with each step, and hence . . . find themselves WAY past the nest by the time they stopped counting.
Just an example of how innovative thinking can result in a clever way to prove a hypothesis.
What evidence led the scientists to hypothesize that ants might be counting their steps? What observed behavior might indicate that was the case? Can you draw me a map of a nest and its surroundings that would demonstrate what the evidence might look like?