The high-frequency sight words used in SIPPS were selected from the 1,000 most frequently used words in school material compiled by Carroll, Davies, and Richman (American Heritage Word Frequency Book, 1971).
For a complete list of the high-frequency sight words in a given level of SIPPS, see the "Sight Word Index" or "High Frequency Word Index" in the Appendix of your SIPPS Teacher's Manual.