Rule 21 refers to 'al' as a beginning. All, written alone, has two l's, but when acting as a prefix only one l is written.
For example: al most, al ways.
Watch the tutorial videos below to see how the Spelling Tools, Spelling Rule 21 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.