If you can get hold of some, get some well-rotted natural compost and give the students a tray of the stuff. They work in pairs with a science beaker and pick out all the bugs and creepy-crawlies they can find keeping a tally. My group did this and it kept them busy for a whole hour and they loved seeing who could find the most worms, centipedes etc. I was staggered. You can get them to identify what they find by type - has it got 4 legs? 6 legs? 8 legs?. Does it have an exokeleton etc?
Sounds a good idea - there should be tons of science work related to gardening clubs...
You could try mixing soil samples with water (in a glass jar) then letting it settle to see what the soil is made of.
Sieving and filtering....??
Internet research and children's on-line garden clubs.... there must be one... if not BBC site?
Design a scarecrow using empty lemonade bottles? Then make the winning design.
Keep a planting / growing / picking diary and add photos.... again using ICT.
Draw plans and record what is planted where - crop rotation for later.
Design: seed packet labels, poster to parents to come and view / buy the produce....
Produce a "Growing Tips" magazine and ask parents / grandparents to contribute and publish once a term..... You might even be able to invite people in to help / work with / talk to the children.
Ours go to a wholesale nursery for the day...It is huge.... all sorts to look at including propagation, potting on, growing, trees / shrubs bedding plants....then they come home with a small plant to grow on as a competition.
They could:
Make a model Shed and include a veg patch outside.... for this you could use a cardboard base, give the net of a cuboid and a triangular prism for the roof - glue the two together. Older children could make their own from scratch using card or square dowel and jinks-corners to make the frame.... Fit out the inside with tools , chair and model camping stove & kettle.
For the garden around the shed - use crepe-papers, pipe-cleaners and anything that takes their imagination to represent the plants...sphagnum moss is great as is glued on and then painted saw-dust. .corrugated cardboard for furrows..... cocktail sticks (ends cut off first with toe-nail clippers) for canes and stakes.... green wool / string for runner bean plants.....
Anyway..... sounds like fun!! Good luck!
When I retire I think I might enjoy going back to work!!