Abstract: A junction ball for connecting two passageways in a modular playground at any desired angle utilizing two rotatably interlocking hollow half spheres having one access port each. The halves are adapted to be fitted together, rotated to produce the proper angle, and locked into place. A single half may be used for terminating a passageway in conjunction with a viewing dome. The modular half spheres are preferably molded in one piece from plastic. The spherical view port is preferably constructed from polycarbonate. These components are supported by and mounted into a standard pipe structure consisting of pipe and assorted clamps.

Abstract: The recreational equipment junction box of the invention comprises a quarter cylindrical hollow box which may be modified and configured in various ways to adapt to the designed application. Primary modifications include number and location of connected tubes, windows and ventilator panels. A further modified use for the junction box is as a control center, simulating the appearance of a vehicle cockpit.

Abstract: The invention disclosed comprises a combination ladder and stair for use by children which incorporates stair-like treads and risers with ladder-like rungs to achieve safe climbing activity. The combination ladder and stair is adapted to be used at a comparatively steep angle to the ground with the treads being maintained level. The rungs are placed adjacent to and level with each tread to afford additional security for the foot, and are spaced from the tread to allow the hand to grasp around the rung. In the preferred embodiment the ladder is incorporated into a split tube which serves as an entry to a children's play system.

Abstract: A puzzle is provided, according to the preferred embodiment, having a series of rectangular blocks assembled so as to be able to slide on the surface of a rectangular planar back panel mounted in a vertical orientation. A set of four frame members, two of which have engaging tongue members and two of which have engaging groove members, are attached thereto. Each of the rectangular blocks is configured with two perpendicular, adjacent edge tongue members and two perpendicular groove members oriented to mutually engage respective tongues and grooves of other blocks and of the frame members of the puzzle. One space substantially equal to the size of one block is left empty to permit block movement. Each block has a magnet adapted to releasably engage a complementary magnet on the back panel so that when the magnets are engaged, the block positioned above an empty block space will not fall into that space.