Esperanto in Scotland, Chapter 1, Exercise 1
Sample answer (yours may differ, as long as the evidence fits the claim).

Claim: "Esperanto never mattered in Scotland."
  Look for: records of how many clubs and members existed, and of what they did (congresses, classes, publications).
  Where: club and Federation reports, Scottish newspapers of 1906-1913, Esperanto periodicals such as The British Esperantist, and the 2025 study Postcards, Translators and Esperanto Pioneers.
  Care needed: membership figures come from club reports and the press, which may be promotional.

Claim: "It was a men's movement."
  Look for: women's names in club office-holders' lists, delegate lists, exam certificates and correspondence.
  Where: the John Beveridge Collection at the University of St Andrews, newspaper reports of club meetings, congress attendance lists.
  Care needed: the absence of a name in a record is not proof of absence from the club.

A good answer names a kind of evidence, a place where it is kept, and one limit on it.