Historically, if a girl child expressed a desire to do "boy" things, parental and authoritative figures discouraged this. This applied to boys who liked "girl" things as well. Rigidly defined gender roles didn't allow children to express themselves naturally. This form of discrimination and lack of tolerance is known as gender bias and is against the law in most democratic societies today.
Gender equality starts with the teacher setting a nonsexist classroom environment that does not stereotype gender roles. An environment that recognizes students equally, regardless of sex, is the first step in teaching gender equality. Children first learn what they live and the teacher sets this tone.
Teaching children gender issues starts with using gender-neutral language. Choosing to use plural pronouns instead of masculine or feminine ones helps avoid gender specific language. In using traditional children's music in the classroom, switch out the "Mary had a Little Lamb," to "Johnny" instead of "Mary." Involve students in discussions about gender issues and have them help to solve gender-related problems that may come up in the classroom.
A classroom's environment should create a safe haven for gender diversity instead of creating one of stereotypical roles. Provide alternatives in the classroom to the "pretend" kitchen -- instead set up an office, a workbench or a hospital scenario. Provide images of men and women in non-stereotypical roles, such as women as firefighters or men as nurses. Show boys and men participating in domestic tasks and caretaking roles previously assigned to women. Depict girls and women in leadership roles and having occupations in science and mechanics.
Select children's books that display gender diverse roles that counter gender stereotypes. Provide magazine cutouts and pictures that display diverse family units as opposed to the traditional stereotypical ones. Some families have mothers and fathers, some only have a mother or a father, while some families have two mothers or two fathers. Provide an environment where children understand and learn to accept diversity in multiple ways.