Zig-zag growth

Lay pre-germinated seeds on a sheet of blotting paper between two panes of glass, pull rubber bands around the panes and place in a water container in a window. Turn the glass panes with the shoots onto a different edge every two days. The roots always grow downwards and the stem grows upwards.

Plants have characteristic tendencies. Their roots strive towards the middle of the earth and the shoots go in the opposite direction. On slopes the roots of trees do not grow at right angles to the surface into the ground, but in the direction of the middle of the earth.