Rule 16 refers to the phonograms 'si'. The phonograms 'si' may also say 'zh' such as in vi sion.
For example: cor ro sion, in va sion.
Watch the tutorial videos below to see how the Spelling Tools, Spelling Rule 16 and Reading Tools are used to spell challenging words.
Special Note:
Not all words will follow the spelling rule. These are called exceptions. If 90% or more words follow this rule then this is still a great tool to help become a proficient speller. Language experience will deal with the rest.