Take a spelling test and track your progress: Longer oi and oy words (JESS).
In longer words, use oi in the middle of a syllable. Use oy at the end of a word or the end of a syllable.
"This is a fantastic opportunity for our students! I'm sure Spellzone will be invaluable in helping them to improve their spellings and therefore improve the quality of their writing in all subject areas!"
Teacher, High School, UK