What is an easy way to remember who puritans were

Well because Puritans were a group of people with religious moral beliefs this means they were very spiritual and religious, which reminds me of the word pure.
Because religious beliefs require you to have a pure, clean heart before God, this could remind you of the word puritans, pure-itans --  because Puritans were religious.

Also, puritans were a group of English Protestants, that can also help you! Protestants - puritans, both start with P and when you remember the word protestants you'll remember that they protested against the church of England under Queen Elizabeth to change and simply forms of worship because they knew it was not the way it should be.

Lastly, Puritans came right after the Pilgrims in the 1630s. Both these words start with P also and they will remind you that Puritans had a great influence in the world just like the Pilgrims. The puritans grew discontent with how the church of England had become (just like the pilgrims) and they wanted to change it. The Puritans brought a huge impact on the church of England with their Christian passion and beliefs. Both the Pilgrims and the Puritans sought to make a difference in the world in light of their faith and beliefs in God. They both brought a new religious freedom to the world by sharing their Christian faith to the world.
The pilgrims will help you remember who the puritans were :)

So, Ways to Remember 
1. PURE-itans (they were members of a religious movement) remember the "pure" in puritans
2. Puritans were Protestants - both start with P (reminds you that they protested against the Church of England & the forms of worship practiced)
3. Puritans and the Pilgrims - (both start with p) remember they shared the same beliefs! and they both fought for their Christian faith and had a huge impact on the Christian church!

Hope this Helps!! Let me know if you have more questions :))