Listen to the sound y makes in the word. Sort by the sound y makes.
city
study
reply
copy
gym
yolk
cycle
yogurt
mystery **
y sounds like long /E/
y sounds like long /I/
y sounds like short /i/
/y/ like in yellow
Look at the end of the word. Sort by it's suffix.
copied
replied
studied
cities
studying
replying
-ed
-s, -es
-ing