Sequential processing is the ability to receive, process, store, retrieve and utilize information in the specific order received by the senses.  This is where we see some children having the ability to follow two step directions only.  However, they are ten years old.  Either they are presenting with being easily distracted and will take in up to six or seven directions like go upstairs, take your bath, dry off, get dressed, don't forget to brush your teeth, call me when you are in bed ... but eventually you make it upstairs to check on progress, the child is sitting on the stairs playing with cars, for example!   Nothing was started or the process was interrupted.