kids a "window to the world underground" by building a root-view box. It's a
structure that allows kids to peek through a glass or plexiglass window to see
what happens underground as a plant's roots grow.
you need is a planter box with a hinged door that you can open. You can add a
plexiglass door to a planterbox with hardware store hinges.
a more elaborate building plan:
basic idea is to fill the box with potting soil, and plant the seeds or
seedlings up against the glass for best viewing.
you'd rather not bother with wood and plexiglass, students can create root-view
boxes with a milk carton, duct tape, cellophane, and black paper.
the top of the milk carton and, with a utility knife (with adult supervision or
perhaps the adult should do this part), cut a long window in one of the
vertical sides. Tape cellophane to the inside of the window to cover it.
the box with soil. Plant seeds near the edge closest to the cellophane.
the box with black paper. Leave the top open for the plant to grow. Secure the
black paper with tape or a rubber band.
box is perfect for observing roots over a short period of time. If students
wonder why the window needs to be covered, suggest that they create a second
box and leave the window open to the light to see what happens. (They'll
discover that roots have a negative tropism for light - they won't grow!)