Autumn is a wonderful time for photography, especially children, as fallen leaves create both an interesting prop and look great. Shooting images in the dappled light of a wood or forest is a must.
Preparation is key and depending on the age of the children you may want to think about taking along items that they can play with. For example, helium balloons, conkers or a small ball, even food such as pears and apples can be appealing in photos. Other props may include wellies and flat caps and you may also want to compliment the natural colours with brown and green clothing.
Typically, a shot of the children picking up a large bunch of leaves and throwing them in the air can look exciting, however you must watch your shutter speed. If you can adjust it to around 1/400 of a second or more. Depending on your level of experience and the complexity of your camera, you may wish to increase the ISO setting. The effect of this will be to allow you to shoot at a high speed without it resulting in an under exposed (dark) image.
I hope this has been helpful – happy shooting.