(CNN) Every so often a boy shows up to school at Garden Oaks Montessori in Houston wearing nail polish or a headband. When that happens, children -- and, sometimes parents -- ask questions.

But Principal Lindsey Pollock is confident her staff knows what to do. They have been trained to support children who deviate from gender norms, whether it's a boy in girls' clothes or a child who was born a girl and wants to be called a boy. And, they know it's school policy.

"Diversity is a good thing. We all benefit from the unique characteristics that we all have," Pollock said. "Our goal is to build a culture of inclusivity and understanding and a mindset of being welcoming to everyone."

Across the country, schools are adopting similar mantras for transgender and gender nonconforming children in their mission statements and policies. Advocates say the efforts reflect growing support for research showing the negative effects of enforcing fixed ideas of what it means to be a boy or a girl on children, especially in learning environments.

Gender Variant: When your gender identity or expression is different from your physical sex characteristics or birth sex.

Gender Expression: The way a person presents themselves to the world through clothing, hairstyles, toys and other preferences. Most people's gender expression matches up with their physical sex characteristics or birth sex.

Gender Identity: How you feel you were born to be -- masculine, feminine or somewhere in between. This identity doesn't always match up with your biological sex, or the gender you were assigned at birth.

"This is the reality in which we live: Gender is a continuum, not a box," said Graciela Slesaransky-Poe , dean of Arcadia University's School of Education in Pennsylvania. Her experience with a gender-nonconforming child led her to become a consultant who has helped schools across the country learn to accommodate children who are opening up about gender identity as early as kindergarten.

"We need to be sure we don't create structures and artifices to reinforce binaries that limit and constrain the ways in which we behave and express ourselves."

The efforts are not always welcomed by the community. Opponents of California AB 1266 are working to get it on the ballot for veto referendum . This week, a Nebraska parent raised objections over training for Lincoln Public School staff about lesbian, gay bisexual and transgender issues.

In an email to parents, the mother cited handouts, including one called "12 easy steps on the way to gender inclusiveness" that recommended against "gendered" expressions such as "boys and girls," the Lincoln Journal Star reported . The mother and school district did not respond to CNN's request for comment.

"By sidelining academic teacher training and replacing it with social re-engineering, the LPS administration has placed a higher priority on social reformation than on education," the mother said in an "introductory speech" prepared for an upcoming school board meeting, according to documents obtained by the Journal Star

Advocates say improving school climate and legal protections are important because transgender and gender nonconforming children are frequent targets of bullying. A 2012 survey found that 42% of gender nonconforming students feel safe at school, compared to 62% of their gender conforming counterparts. More than 40% of students who participated in a 2005 National School Climate Survey felt unsafe at school because of their gender expression; 26% said they were physically harassed the previous year because of their gender expression.

"The work that we do is not to make schools safer just for transgender students, but to make schools safe for everyone regardless of where they fall on the gender spectrum," said Kim Westheimer, director of the Human Rights Campaign Foundation Family Project's Welcoming Schools initiative. The program helps schools, such as Garden Oaks Montessori, create an inclusive climate through staff training, policy recommendations, and bullying prevention approaches.

Creating a welcoming environment is an ongoing process that involves various stakeholders from the school community. Here are some steps that educators, parents and advocacy groups recommend for creating a gender inclusive school community.

1. Don't separate children by gender

When it's time to work in groups, experts recommend coming up with alternatives for separating children. The first letters of their last names, birthday months, clothing colors or types of pets they own are just some ways to do it, but many more exist.

Separating by categories other than gender helps children identify and build relationships based on common ground -- or, at the very least, start conversations. In other words, it helps them learn to relate to others based on similarities (and differences) other than gender.

2. Start the day with inclusive language and stick with it

Instead of saying "good morning, boys and girls," experts recommend using broader language to convey a sense of equality and togetherness. Again, a variety of alternatives exist, such "good morning, class" or "good morning, everyone."

Using inclusive language throughout the day reinforces the idea that boys and girls are not limited by their biology to succeed in the same arenas, said Rhonda Thomason with Welcoming Schools. Often, we imply that boys or girls are only good at specific things through the subtle (and not-so-subtle) things we say, or the activities we nudge them toward.

3. Feature diversity in books, posters and other workbooks

A wide selection of children's books feature transgender and gender expansive children. Many more feature men and women in nonstereotypical roles of all races and sexual orientation; the same goes for posters that hang in classrooms.

4. Create a professional development plan to help educators

Some schools devote several administrative prep days to familiarizing staff with issues surrounding transgender and gender variant children. After all, teachers set classroom tone through language and lesson plans. They also can intervene in instances of bullying or name-calling and, when appropriate, use them as teachable moments.

In order to act, experts say educators need to develop a shared understanding of gender identity and language to be able to communicate with students and parents. But they need to know what to look for, and they need to believe that they have the support of the school, which leads to the next suggestion.

5. Have strong policies to support transgender students

Some schools may not know what do if a child who was referred to by male pronouns now uses female pronouns. What does that mean in the classroom, or on their transcript?

Policies should address how to handle names and pronouns, bathroom use, extracurricular activities, student records, and confidentiality, said Westheimer with Welcoming Schools. These issues can be complicated, so best to consult an expert in your area or national organizations such as Welcoming Schools Gender Spectrum or TransYouth Family Allies

6. Engage the entire school community

Each school approaches this differently. One school in Maine sent a letter home to parents informing them that a second-grader who identified as a girl the previous year would be recognized as a boy this year. Others incorporate the discussion into class or school-wide meetings.

The goal is the same: to set community norms for what's expected and create a platform for people to ask questions.