Explain the secret that Fritz told Gerta. Why didn't they tell their mother the secret?

Read the sentence. marissa heard the class bell ringing loudly walking down the hall. what is the best way to revise this sentence? `marissa heard the hall ringing loudly walking down by the class bell. `marissa heard the class bell walking down the hall ringing loudly. `walking down the hall, marissa heard the class bell ringing loudly. `walking down the hall, the class bell ringing loudly marissa heard.