Google Classroom
GeoGebraGeoGebra Classroom

Ladder (3D)

You can use the Navigation Bar (on the bottom) to follow the construction step by step. In this case is recommended to show the objects behind the construction. Use theToolbar Image Show/Hide Object tool (in the last icon) for this. To refresh to original construction just press on the cyclic arrows in the right top corner.

Move the blue point and observe the stairway's movement.