Complex sentence: In making the point that any mode of instruction that tired the attention was hurtful to children, her reasoning was that people can pay attention only to one thing at a time, and because children can appear resistant to repetition, teachers naturally should vary things.
Split into simpler sentences: In making the point that any mode of instruction that tired the attention was hurtful to children. Her reasoning was that people can pay attention only to one thing at a time, and because children can appear resistant to repetition, teachers naturally should vary things.