She started to see a part of her husband in Sammy, and she saw Nanny as more meek than she, and she did not want her children to succumb to weakness.
Sarah's desire for a better life for her children led her to take a stand against Adoniram. She had to show her children how to be strong and independent, and by moving into the barn, she was trying to teach them a lesson. She did not want her children to suffer because they did not know how to stand up for themselves. When Adoniram first confronts Sarah about moving, Sammy gets up and stands in front of her, as a way to protect her, which shows that he learned from his mother's example and stood up for what he believed is right. The message was meant for Nanny, but she cowered behind her mother, meaning that she is still not standing up for herself.
Sammy's eagerness in telling his father that the family had moved into the barn further demonstrates that Sarah has really taught her son how to stand up for himself, and he was anxious to test his newfound confidence. Adoniram was frightened when he walked in the new house. He did not know what to do when Sarah took control of the situation, and he for the first time, would be obedient to Sarah.
Just as Sarah asserted herself against her husband in "The Revolt of Mother,'" millions of women have since then and still do today. A