Ten. Eleven. Twelve. Those are the ages that for many girls, the world becomes a much more dangerous place.
For the 250 million adolescent girls in poor countries, the world often becomes smaller as they approach puberty.
One in seven girls is married by age 15. Few, if any child brides have a choice about who they marry or when.
Early marriage isn't the only reason that nearly three-quarters of the children who don't go to school are girls. They're still the ones who are required to stay home to care for younger siblings or work in the fields.
In many developing countries, girls have no access to menstrual products. That means for one week every month, they can't leave their homes to go to school.
And because girls are less likely than boys to go to school, by 2015 women will comprise two-thirds of the world's illiterate. It's a terrible waste that dooms many more children to poverty.
Studies indicate that an educated girl will invest 90 per cent of her future earnings in the family, compared to 35 per cent for a boy.
In many places, the myth that sex with a virgin will cure AIDS remains. In too many others, younger and younger girls are bought for sex by men afraid that older girls and women may be infected.
Even in Canada, girls face challenges. They have higher rates of depression.
More than 20 per cent of B.C. girls say they have deliberately cut or harmed themselves, according to the McCreary Centre Society, a non-profit aimed at improving youth health. It also reports that more than half of all girls say they wish they were someone else. More frighteningly, Canadian girls aged 13 to 15 are at greater risk of being sexually assaulted than young women aged 18 to 24.
And tragically, close to three-quarters of aboriginal girls under 18 have been sexually assaulted.
Nearly 70 per cent of Internet intimidation is aimed at young girls and women.
Ten. Eleven. Twelve. That's Thursday's date - the first United Nations' International Day of the Girl, an initiative led by Plan Canada to recognize that girls face "double discrimination because of their age and gender."
Nowhere is the discrimination girls face so plainly visible as in India.
On Tuesday, the Indian government released a report that suggests selective infanticide over the past decade has resulted in nearly one million 'missing' girls.
Yet it's all too easy to point fingers. Some of the most threatening issues for girls in developing countries also exist in Canada, although they are better hidden in reclusive ethnic and religious communities.
For years, girls from the fundamentalist Mormon sect in Bountiful, B.C. have been forced and even trafficked into marriage.
Those girls - along with boys - have rarely graduated high school even though their schools have been publicly funded.
Selective abortion based on gender is a recurring issue in South Asian communities and within the last few years, Canadians have been involved in so-called honour killings where girls are killed by family members for their supposedly shameful behaviour that usually involves dating boys outside their tight-knit community. But aboriginal girls are the most disadvantaged in the country. By every health, social and educational index, they lag all other girls. It should be a national shame that of the 100 Inuk children who start kindergarten in Nunavut, only 25 will graduate from high school.
Across Canada, aboriginal girls and boys account for 40 per cent of the children in government care.
And, according to a study done in 2000 for Save the Children, commercial exploitation of aboriginal youth and children accounts for more than 90 per cent of the visible sex trade.
Across Canada, girls confront the truly First-World problems of body-related issues such as obesity, eating disorders and hyper-sexualization because of over-exposure to media images.
A single day, once a year won't cure the double dose of discrimination poured onto the tiny shoulders of girls.
But education can. If even for one day, people pause and ask why girls can't have the same opportunities as boys to fully develop their unique abilities, perhaps change will come more quickly.