What skill does a student need to develop if they write "jaz" for jazz and "tos" for toss?

The student is demonstrating difficulties with encoding or spelling words accurately. When writing "jaz" for "jazz" and "tos" for "toss," it indicates that they are not applying the appropriate spelling rules related to the doubling of consonants, specifically the "floss rule." This rule states that in certain one-syllable words that end with a short vowel sound, consonants are doubled before adding a suffix or in their standard spelling form.

For example, in the word "jazz," the final sound is the voiced /z/, which is doubled after the short vowel /a/. Similarly, "toss" features the final /s/ sound, which follows the same pattern. Thus, the student's misspelling suggests a need to develop their understanding and application of the floss rule to improve their spelling accuracy in words that adopt this convention. Mastering this concept will aid them in correctly identifying when consonants should be doubled in similar contexts.