I have a wonderful way a child can learn shapes in the science area. Cut out several of your desired shape from cardboard, or heavy paper (for instance 3 circles). On each one add different textures to them. One might have sand, another cotton, and another might have aluminum foil. That way their learning the shape, while feeling different textures.
Instead of going on a nature walk, the class can go on a Shapes Walk. As the kids walk around the school campus or go on a little field trip, they can point out different shapes. Or you can ask them if they can point out a circle and so forth.
When teaching shapes in my group day care home we learn that two of the same shapes put together make a totally different shape. Two squares put together make a rectangle, two triangles make a diamond., two hearts, well they just make two hearts.