The Basic Spelling Vocabulary List
This list was devised to help educators know which spelling words should be taught to children. The list contains 850 words that account for 80 percent of the words children use in their writing — the ones they need to be able to spell correctly.
Mastering this relatively small corpus of words yields a high rate of return. For example, the most common 1,000 words are used 13 times more frequently than the next most common 1,000 words. It also provides teachers flexibility in planning spelling instruction, providing an opportunity to give children the "basics" while supplementing with other spelling words germane to classroom activities.
Grade level for each word was determined based upon difficulty, pattern of occurrence in children's writing across grades, and grade placement on current vocabulary lists and spelling materials.
Read the list here