Make the sentence negative. Use the short form of the auxiliary verb. Girls in ancient Egypt attended school.

1. Identify the auxiliary verb: 'attended' is in the past simple tense, so the auxiliary verb is 'did'.
2. Form the negative: Add 'not' after the auxiliary verb and use the base form of the main verb.
3. Apply short form: Use 'didn't' instead of 'did not'.
Final Answer: Girls in ancient Egypt didn't attend school.