The term derivational relations emphasizes how spelling and vocabulary at this stage grow primarily through derivation: from a single base word or word root, a number of related words are derived through the addition of prefixes and suffixes. Students at this stage are at a more advanced level of word knowledge, which means word study focuses as much on vocabulary development as it does on spelling development. Analyzing the spelling of words supports vocabulary growth, and vocabulary growth in turn provides helpful support for higher-level spelling development.