Grammarly
Grammarly Blog: I Before E Except After C: 9 Helpful Spelling Rules
This site provides nine important spelling rules and examples. L.9-10.2c Spelling, L.11-12.2 Cap/Punc/Spell
Dave's ESL Cafe
Dave's Esl Cafe: Verb Forms and Verb Tenses #6: Spelling Ing Forms
Spelling rules and examples for adding the "ing" suffix to the ends of words.