Monthly Archives: May 2019

Beanz meanz tweetz

Here, as requested (many times! thank you!) are the details of how to set up the Bean Mineral Ion Deprivation Experiment. It does need a bit of planning….

Start by ordering the relevant kit from Philip Harris or Timstar (just shy of £30 – does enough for about 40 groups). It’s the Sach’s Water Culture set or Plant Water Culture set. You actually get 9 different minerals in the set – so there’s lots of scope for investigations…

Sach's kit.JPG

You will also need beans. We use Sutton’s Dwarf Broan Beans (£2.99 for pack of 45) as they sit better on top of the boiling tubes. You’ll need 5 beans per student/group so do a few more to allow for wastage. A week before the lesson,  soak the beans in water for 24 hours and then germinate them; a layer of damp vermiculite in a tupperware box works well…

beans 1

Each group needs:

  • 5 boiling tubes
  • boiling tube rack
  • something to label the tubes with
  • parafilm/clingfilm
  • mounted needle
  • access to the following solutions…
    • distilled water
    • normal
    • –  magnesium
    • – nitrates
    • – phosphates
  • 5 germinated beans at same stage of development – must have a prominent radical…beans 3

The radical doesn’t need to be this long, but it must be there. Warn your students to handle them carefully – they snap quite easily!

Students then label the test tubes accordingly and add the relevant solution. The tubes must be filled to the brim as the radical must make contact with the liquid.

Then they put a piece of parafilm or clingfilm over the top of the tube and make a small hole in it with the mounted needle. Make sure the film has a slight depression for the bean to sit in.

beans 2

Then they carefully insert the radical through the hole…

beans 4.JPG

Repeat for all solutions and leave for a week. Keep an eye on the water levels in the tubes – top up with a pipette if it drops below the level of the radical…

There are really lovely clear results in a week. Beware that as the beans grow, the extra rootage and leafage drains the water in the boiling tubes very fast, so if you want to keep them going, you’ll need to transfer them to a beaker or plant them out.

Enjoy! Let me know how it goes…