Complex sentence: During this time the instruction was also expanded to include memorization of the Lord's Prayer and Apostles' Creed, and some clergy probably provided expositions of this material in addition to the Ten Commandments.
Split into simpler sentences: During this time the instruction was also expanded to include memorization of the Lord's Prayer and Apostles' Creed. Some clergy probably provided expositions of this material in addition to the Ten Commandments.