One of the most famous lists of spelling words in the history of reading instruction is the Ayers list. It was developed with tests of thousands of children in schools throughout the United States in 1914 and 1915. The most common 1,000 words at that time were tested. You can test your children today using the Ayres scale and see how they compare with children taught with good phonics and spelling programs in the early 1900's.
The book that Ayres wrote explaining his scale and how to use it to test a classroom of children or an individual child is called "A Measuring Scale for Ability in Spelling" by Leonard P. Ayres, 1915. It is free online from Google Books. Instructions on how to give the test to an individual student are on page 37, the scale you'll need to reference is on page 28, and the word lists you'll need to use start on page 51.
The Ayres test will give scores that are based on the averages of children in 1914 and 1915. Spelling scores have declined since then with the advent of sight word teaching, invented spelling, and a decline in phonetic spelling instruction with the explicit teaching of the phonetic rules that govern spelling. By 1953, spelling scores had declined 2 grade levels for the upper grades and 1 to 1 1/2 grade levels for the lower grades. (40L volunteers have compared spelling word lists and scores for words given using the same procedures in 1922 and in 1953. You can see the lists and scores for 1922 online: "The Iowa Spelling Scales" by Ernest J. Ashbaugh, 1922. The 1953 test results are found in "The New Iowa Spelling Scale" by Harry A. Greene, 1954.)