Wallace was an excellent thinker, but it takes practice. Some activities ask you to come up with your own ideas. This will give you an insight into how a scientific theory develops.
Primary sources are the letters, notes and notebooks written by people such as Wallace during the historical period you are studying. They include photographs, certificates and other documents.
Secondary sources are articles and biographies about Wallace. These might contain opinion, speculation and bias. Watch out for factual errors.
When you write an opinion or a conclusion, provide evidence to back it up. This is usually a direct quote, for example, from a letter.
Always include the reference to a source, so people know where you found it. For example, if you use one of Wallace’s personal letters, write the following:
'By permission of the Board of Trustees at the Natural History Museum:
[Author of letter, date of letter, title of letter, catalogue number (eg. WP1/3/24), full website URL and date you accessed it]'.
You can include this as a numbered footnote at the end of your text rather than including it in the body text. For further advice on giving references, ask your teacher.