"Material that supplements the content of the paper, but would be distracting or inappropriate to include in the body of the paper is to be placed in an appendix." This includes "materials that are relatively brief and that are easily presented in print format" (Publication Manual of the APA: 6th edition, section 2.13; Publication Manual of the APA: 7th edition, section 2.14). Examples include "mathematical proofs, lists of words, a questionnaire used in the research, a detailed description of an apparatus used in the research, etc" (Purdue OWL.)
Where is an Appendix Placed?
An appendix (or appendices) follow the reference list. Use the following order for your paper:
Abstract (if required, start on a new page, numbered page 2)
Text (start on a new page, numbered 3)
References (start on a new page)
Tables (start each on a new page)
Figures (start each on a new page; include caption on page with figure)
Appendices (start each on a new page)
Labeling the Appendix
If only one appendix, label it Appendix
If more than one appendix: label each one with a capital letter (Appendix A, Appendix B, etc.) in the order in which it is mentioned in the text
Each appendix must have a title
In the text, refer to appendices by their labels:
"produced the same results for both studies (see Appendices A and B for complete proofs)."
Formatting the Appendix
Begin each appendix on a separate page
At the top of the page, center the word Appendix and the identifying capital letters (A, B, etc.) in the order in which they are mentioned in the text.
Center the title of the appendix using uppercase and lowercase letter on the next line
Begin the text of the appendix flush left, followed by indented paragraphs.