Critical thinking skills allow you to analyze a Primary Source to gather as much information as possible from it. Using your own experiences and prior knowledge of a historical event, much of which you develop when you read books and other secondary sources about a topic, you can raise questions and problems about the sources that help you determine whether or not the source is useful for your project.
Critical thinking skills recognize that human beings have limited perception -- we just can't see and comprehend everything that happens. Understanding this fundamental fact is essential when considering your own or instructing students in the use of critical thinking skills with primary sources.
Questions to ask your Primary Sources
What type of document am I looking at? A letter, a financial form, a newspaper clipping, etc.? Is it typed or handwritten? Does that matter to your understanding of the document?
Who created this source, and why?
What was the original audience for this source?
What was this document's original purpose?
What was happening when this source was made?
If this source shows a specific point of view about a historical event, is it possible to find an alternate point of view?
What did you find that surprised you about this source?
What can I learn from this source that is new to my research/