Imagine a world where girls and young women are seen and heard, occupying positions of influence within their communities and beyond. On this very day, you won't have to imagine: girls will be stepping into the shoes of political, social and economic leaders in a mass takeover that will make their invisible lives - both their plight and their potential - truly visible.

There will be over 200 takeovers in more than 50 countries. From the President of Nepal to the Minister of Finance in Canada, leading figures will be stepping aside. In Guatemala and Uganda, girls will take over senior roles in major banks; in Guinea-Bissau, a young woman will co-host a national TV debate. In China and Thailand, girls will take their teachers' roles, and in Timor-Leste a girl will become Vice Minister of Education. 

In Bangladesh, girls are standing up and contributing across different sectors, as the Divisional Office Manager in Rangpur and Barisal, in the private sector as Vice President of Talent and Development of telecoms provider Robi, and right here in our own offices, as Country Director of Plan International.

When girls realise what is possible, they are more likely to find inspiration and become active agents of change. But the takeovers also provide an opportunity for those stepping aside to work with young women, to listen and to learn; to find out from them directly how they want to change their lives for the better.

Things need to change. In every walk of life, in every corner of the world, girls face discrimination and injustice. Millions are denied their rights to a good education. They are unable to play an active and equal role in society. They are prevented from making important choices that affect their own lives, including decisions about sexual and reproductive health. They are often at risk of violence, simply for being a girl. 

Things can change. Last year the UN agreed on an ambitious set of Global Goals that promise gender equality by 2030, among other things. While the challenges in achieving those goals are vast, they are not insurmountable, if we act and act now. It will require a clear-sighted agenda for change based on six key elements.  

First, we need to get the legal framework right. There are currently few direct mentions of girls in key international human rights instruments and, until that changes, girls will remain invisible. We need to build a movement to bolster those rights, and to drive change more widely. 

A strong, grass-roots movement for girls' rights has emerged in recent years. We now need to strengthen and sustain that movement, building solidarity with the girls and young women who are already at the front lines demanding their rights. Our global 'takeover' is just one way in which we plan to grow that movement. 

However, while the UN's Global Goals represent an impressive statement of intent, they are just words unless governments act on the commitments they have made. We need to be ready to help countries deliver, but also to challenge them when they do not.

If we are going to hold governments to account, we need better data and we need to use it more effectively: girls are 'invisible' to policy-makers because they are not being counted properly. Better data is also vital to making the right kind of decisions and investments that can transform girls' lives.

Transformative change also requires new ways of working. We need to involve everyone, and the private sector has just as much of a role to play here as NGOs. Only by finding new ways of collaborating will we be able to find new solutions to complex problems. 

Finally, we need to get the resourcing right. Just meeting the worldwide need for pregnancy-related care will require USD28 billion annually, a 100% increase from current funding. We'll need to be smarter about using all of the resources that are available, including working with the private sector.

If we are serious about reaching the Global Goals, we need to get serious about making change happen. The six changes are a map; our girls' takeover is the compass, setting the direction in which we need to travel. Girls will step into some of the biggest shoes, from presidents to business leaders to head teachers and journalists. It is a powerful glimpse of the world we want to see. Our challenge is to make a future in which every girl has the chance to become an important presence, and for more than just one day. 

The writer is CEO of Plan International.