Seed to Sandwich link (20 min)
Compare the set of photographs to see evidence of growth. Note how long the process has taken and when it was quickest – warm months. Remember that the pests, diseases and weeds will also have grown rapidly at this time (not just the crop) and this is the challenge for the farmer. When we did this activity we used our own photographs, which are not yet on this site, but we have since found an equivalent on the education wing of the National Farmers Union website, known as 'field-to-fridge' -
check-out http://www.ukagriculture.com/field_to_fridge_face/fieldtofridge_face_htm to go straight there and follow the growth of a number of different crops.
Microbial growth & its control (30 min)
The children are each given a piece of bread and cut it into two – wet both halves with a few drops of water. Additionally spray a dilute solution of bleach onto one half only – must be done by an adult! Place on a plate or in a shallow tray, cover with cling-film and place somewhere warm. Leave for upto a week and examine. Spores from micro-organisms are all around us, although we can’t see them. They land on the bread, germinate and grow giving symptoms of bread mould except were we have ‘protected the bread’ (bleach kills the microorganisms). Best if the bread was a couple of days old when you do the experiment. If you want another variable, cut into 3 and toast one piece (thus drier).
Observing plant growth (1 hour): Mung bean diaries
How will we know if our germinated mung-beans have grown. Consider differences/similarities between germination and growth. Using a tube, provide the germinated bean seed with a support and a water supply using a piece of blotting paper as a wick with water in the bottom of the tube. Although growth is occurring all the time at the cell level we only see the effects over time so measure daily root length, shoot length, count leaves, note shoot colour etc. Setting up this experiment is awkward but it is another scientific skill well worth developing.
Runner Bean Challenge (1 hour)
Provide a blacked-out box with a hole in the lid and a runner bean seed that has been soaked in water overnight. Sow the seed in about 2cm of soil, moisten and then place pieces of card in the box to provide an obstacle course for the bean-shoot in its search for the light – coming through a narrow hole in the top of the box. Keep soil watered and place boxes in the warm and the light.
Physical theatre – the wheat seed drama (15 min)
Out of the lab and into the sports hall for this one! Children are wheat seed, they go through the process of germination and growth responding to your description of events – watering, drought, sunshine etc etc. A great way to round-up the cycle of events in a memorable fashion.
Human Growth (40 min) Potential ICT-link
Take advantage of the extra space in the hall and let’s do some more science.
In advance, challenge the children to calculate their exact age in years and days. Arrange children in a line of increasing age: note smallest children will not always be the youngest, but if growth occurs as they get older why is this not true? Discuss. Investigate other size relationships in humans – eg. height and foot size; length of arm from elbow to wrist compared with foot length.