take a plastic pipe and fix a jet at one of its end.connect the pipe to a water tap attached to a large overhead water tank.fix a large protractor,so that you can hold the pipe at different angles(at 15',30',45',60')
Hold the pipe in such a manner that jet of water comes out of an angle 15' .measure the distance up to which water is reaching.this is the range of the projectile.
Now hold the pipe at an angle 30',45'and 60' .measure the range of the projectile in each case.
keep the speed of water coming out of the jet same in each case.
what do you find?for a given speed,the range is maximum when the angle of projection is 45'.
Also try to find out the effect of initial speed of water on the range of the projectile.