Women's roles in the workforce changed during World War I by recruiting many to work outside of the house.
Many men, and even women, believed that a women's duty lied within the household. They should cook food, clean, take care of the children, and not seek jobs outside of the house. With World War I, a lot of the men were off to war and they desperately needed supplies like ammo, weapons, vehicles, medical supplies, and other war goods.
Since all of the men were off to war, many women took jobs in factories to pitch into the war effort. Many were seen making weapons and vehicles, going away from their traditional "stay at home" ethic.