After completing extensive research, Edward B. Fry, Ph.D. wrote the book
1,000 Instant Words -- The most common words for teaching reading, writing, and spelling.
Dr. Fry's Instant Word List (which is also commonly referred to as Fry's Instant Words List and Fry Words) are the most common words in English ranked in order of frequency. The first 25 Fry Words make up about a third of all printed material and the first 100 words make up about half of all written material.
Given their importance, I provide practice with the first 100 words DAILY in my first grade reading groups.
I also send a copy home for additional practice. It is hoped that students will master these words in isolation, and then carry them over when reading and writing at the sentence level.
Below are links to all 1,000 words.