The National Children’s Museum, a local institution that hopes to have a permanent, full-fledged museum in the coming years, is taking a giant step to increase its interim spaces for children and to maintain its visibility.

The next phase of the National Children’s Museum will have indoor and outdoor spaces

“This is the next step in the creation of a National Children’s Museum as we try to met the demands of families and children in the region,” said Kathy Dwyer Southern, the longtime president of the effort.

This will be the second transitional home at National Harbor for the museum project. Right now the staff runs a Launch Zone, a physical prototype which is open to children and tests some of the ideas and themes of a future museum. Southern said the current facility and the auxiliary outreach programs served 300,000 parents and children in 2011.

Both new areas will be on St. George Boulevard in the heart of National Harbor along the river in Prince George’s County.

The indoor space will be in a pre-existing building. “The interior space is a hub. The exhibits talk about understanding what my role is in the family, the community and the world,” said Willard Whitson, the vice president for exhibits and programs.

The outdoor space will cover 60,000 square feet and be designed as a “museum without a roof,” said Whitson. That area will have a working vegetable garden, exercise activities and materials to build a fort. “These are not set pieces like in a playground. The kids are creating the spaces,” he said. “These are play-based activities.”

The cost is $6.75 million for “A Place for Being Me,”said Southern, who added the new ventures will help with fund-raising for the permanent home.