Originally Posted by Nyaanyaa
accurate historical information
National History Day (NHD) suggests conducting research via primary source documents and artifacts. The US Library of Congress (LOC) and Harvard libraries, among others, provide access to digitized collections of primary sources, including the LOC primary source sets, while museums including the Smithsonian present artifacts. The National Museum of African American History & Culture (NMAAHC) is one example. There is also an International Slavery Museum (ISM) which educates about the experiences of enslaved people, sharing both current-day events and history of trans-Atlantic slave trade. While the museum houses collections of artifacts, an online interactive lesson presents "Enslaved Africans: Our Truth".

Because many primary source documents were written in cursive, being able to read cursive is necessary to "access" these primary sources. Unfortunately, cursive is no longer taught in many US public schools.

Harvard Library Research Guide defines primary sources here and secondary sources here.

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how would one ascertain its accuracy
Often by comparing several independent primary sources for corroboration, a degree of confidence can be developed about the accuracy of the journals, letters, newsclippings, etc.

When reading books such as textbooks, it may be wise to check the list of reference materials. Some books which have helped kids learn about and appreciate history include DK books and Eyewitness to History.