If you wish to blow the seeds of a dandelion, which is a flowering plant with seeds, you can see that these plants spread their seeds with the help of wind, thus dispersing through air. The tiny parachute having silky hairs allows the seeds to go away from the main parent plant and be carried away by the wind.
The biology science fair experiments for schools in this case can be done with the help of models of the seed and its ability to get dispersed.
You can make the main goal of the experiment as the investigation of the size and shape of the seeds and fruits which may have an impact upon the dispersal.
Why the dispersal of seeds is given so much significance, because that only will deliver the constant survival of the species of plants. If plants grow within the vicinity of each other, then you can see that they will be competing for each basic need like shelter, nutrient, light, water etc .Thus dispersal of seeds allows the progeny to spread over a huge space and it reduces the competition between the young ones.
Seeds are dispersed in variety of ways. In fruits like apples, more than one seed will be present within a fruit .The apple fruit is swallowed by many animals and its seeds are spread through their faeces or any undigested food. Some fruits like coconut will be carried away by water and the seeds will base their roots in some other banks of river or in the land, if it is carried out very far. Some fruits like that of pines, burdocks etc. will have spearheads with which they can attach as hooks to the fur of the animal and they get carried to far away places. The Dandelion fruits hang freely from the feathery parachutes which are taken away by the wind.
For the biology science fair experiments for schools, you can just discover the size and shape of the fruits and seeds which have an impact upon the dispersal through wind. You can make your own seed and fruit or choose which is best for you and try to measure the most significant qualities that increase its capacity to disperse in the wind. You can just calculate the distance traveled and time taken to disperse, if you could and you can make a good guess, if you can’t predict properly.
Sailing seeds is one of the experiments in wind dispersal, which you can carry out as biology science fair experiments for schools. You will need artificial fruits and seeds or seeds of dandelion, coconut, peas, nuts, maple, a large fan, stop watch, a tape measure, a video camera if possible and other stationery items like a marker, glue, scissors, paper, pencil, eraser, cleaner, pipe, tape etc. and after taking a complete shot, you can record the events in a paper and make a graph out of it.