Despite recent research on the building blocks of language processing, the nature of the units involved in the production of written texts remains elusive: intonation units, which are evidenced by empirical results across a growing body of work, are not suitable for writing, where the sentence remains the common reference. Drawing on the analysis of the writing product and process, our study explores how children with and without dyslexia handle sentences. The children were asked to write a short story and the writing process was recorded using keystroke logging software (Inputlog 7 & 8). We measured the number of pauses, the nature of the language sequences segmented by pauses, and the revision operations performed throughout the process. We analyzed sentences both in product and process. Our results showed that both the written product and the writing process reflect the establishment of a syntactic schema during language processing in typical children, in line with the first functional step in processing. This was not clearly evidenced in the case of dyslexic children, due to their limited production: beyond spelling, syntactic elaboration was also affected. In contrast, it appeared that the units of language processing cannot be equated with sentences in writing: the information flow is produced through usually smaller bursts that each carry part of the meaning or correspond to a specific operation of text crafting and revision. Keywords: writing; typical children; dyslexia; sentence processing; keystroke logging