The Slider is aDALESTapplication. The user has a magic cube with an invisible 3D object in it. The user can control a laser plane by moving it along any of the axes. The places where the plane cuts the invisible object become visible – i.e. the user can view only the intersection between the plane and the object. The user can also rotate the whole magic cube together with the invisible object in it and examine it from various point of views. The goal is to guess the type of the invisible object by inspecting its intersection with the laser plane

The application has 16 different objects (cubes, spheres, cone, cylinders, pyramids, to name just few of them) shown at various orientations. There are more than 90 problems grouped in 5 sets: "easy", "moderate", "hard", "random" and "conic". The last set is special set with only cones, pairs of cones and cylinders. The application keeps track of users, the solved problems by each user and the time used by users for solving the problems

1. Inspect the intersections of simple objects (cubes and spheres)
2. Inspect the intersections of objects similar to the simple objects (cylinders, cones, pyramids)
3. Inspect the intersections of truncated objects
4. Inspect the conical intersections
5. Guess the 3D object by examining its intersection
6. Find objects which have similar (or same) intersections in one orientation of the cutting plane, and different intersections in another
7. Build a list of intersection features and determine what objects' intersections have them
8. Examine the effect of object orientation over the shape of the intersection
9. Having the 3D object displayed try to predict its intersections
10. Build your own problems with the predefined set of objects