When I was a child my parents always made sure we attended Sunday School. These schools were first set up in the 1700s in England to educate working children.
That's interesting.  Did Sunday School only teach religion or did it cover other school material?
It's aim was to cover the Bible, plus reading, writing and arithmetic.
Are Sunday Schools associated with a particular religion?
The movement itself was cross-denominational. Today, each church tends to have its own Sunday School
Is there a particular curriculum that most Sunday Schools use?  Like lesson plans.
I believe there are lesson plans. There certainly were when I attended and we were expected to study!
Nice. Are Sunday School teachers certified in some way?
wrote an article in his journal, and as a result many clergymen supported schools, which aimed to teach the youngsters reading, writing, cyphering (doing arithmetic) and a knowledge of the Bible.
In 1785, 250,000 English children were attending Sunday school. There were 5,000 in Manchester alone. By 1835, the Society for the Establishment and Promotion of Sunday Schools had distributed 91,915 spelling books, 24,232 Testaments and 5,360 Bibles. The Sunday school movement was cross-denominational. Financed through subscription, large buildings were constructed that
School had 1,127 boys and 1,324 girls on its books when it opened. The building is now known as The Old Sunday School and is part of Macclesfield Museums.
Sunday schools were first set up in the 1780s to provide education to working children on their one-day off from the factory. It was proposed by Robert Raikes, editor of the "Gloucester Journal" in an article in his paper and supported by many clergymen. It aimed to teach the youngsters reading, writing and ciphering and a knowledge of the Bible