What does Booker say he learned about manual labor from Miss Mackie?

Miss. Mackie taught Booker the pride of accomplishment because of the work she performed by his side to make sure everything was perfect...... she was the head mistress, and the condition and cleanliness of the school reflected upon her.

From the text:

During these two weeks I was taught a lesson which I shall never forget. Miss Mackie was a member of one of the oldest and most cultured families of the North, and yet for two weeks she worked by my side cleaning windows, dusting rooms, putting beds in order, and what not. She felt that things would not be in condition for the opening of school unless every window-pane was perfectly clean, and she took the greatest satisfaction in helping to clean them herself. The work which I have described she did every year that I was at Hampton.

Miss Mackie did not hae to clean the windows, but she chose ot anyway to show that nothing is ever perfect unless it is clean and done properly.She did not have experanice in the slave life unlike Booker, but she was still happy to do clean so that her school wold look perfect on opening day.