Any ideas for a science fair project for elementary school?

Answer 1

I remember doing one once on photosynthesis. I took two plant seeds, put them in the same size pots with soil from the source, watered them the same amount and at the same frequency, but kept one on a sunny windowsill and the other in a dark closet. I think I was 2nd or 3rd grade.

Answer 2

Actually I always wanted to do this easy and useful project on tree rings. All you have to do is good a good slab of tree where you can see the tree rings really well, and describe what they tell you...

Many trees in temperate zones grow one growth ring each year, the newest ring being adjacent to the bark. For the entire period of a tree's life, a year-by-year record or ring pattern is formed that reflects the climatic conditions in which the tree grew. Adequate moisture and a long growing season result in a wide ring. A drought year may result in a very narrow one. Trees from the same region will tend to develop the same patterns of ring widths for a given period. These patterns can be compared and matched ring for ring with trees growing in the same geographical zone and under similar climatic conditions. Following these tree-ring patterns from living trees back through time, chronologies can be built up, both for entire regions, and for sub-regions of the world. Thus wood from ancient structures can be matched to known chronologies (a technique called cross-dating) and the age of the wood determined precisely. Cross-dating was originally done by visual inspection. Nowadays, computers are used to do the statistical matching.

To eliminate individual variations in tree ring growth, dendrochronologists take the smoothed average of the tree ring widths of multiple tree samples to build up a ring history. This process is termed replication. A tree ring history whose beginning and end dates are not known is called a floating chronology. It can be anchored by cross-matching either the beginning or the end section against the end sections of another chronology (tree ring history) whose dates are known. Fully anchored chronologies which extend back more than 10,000 years exist for river oak trees from South Germany (from the Main and Rhine rivers). A fully anchored chronology which extends back 8500 years exists for the bristlecone pine in the Southwest US (White Mountains of California).

In areas where the climate is reasonably predictable, trees develop annual rings of different properties depending on weather, rain, temperature, etc. in different years. These variations may be used to infer past climate variations — see dendroclimatology.

Answer 3

You can also do the crystal garden experiment.

Uses salt crystals, some charcol briquets and laundry bluinng