The girls were standing in the only open area of the playground. There are no bars, rings, or poles in the spot, and that is where to dig for the time capsule.
(see related question)
its where the talking girls are standing
Somewhere on playground
By the big nate park.
On Big Nate island the three girls stand on the playground to the right of the school .
by standing by the bell
near the playground
Under the playground
where the chatty girls are.
under the tree house and ropes in the playground
Under the monkey bars on the playground
The Treasure is on the ground where the girls that are ignoring you are
its where the girls were "yakking"