One example of a magic spell suitable for kids is the Pet Blessing from Free Witchcraft Spells. Another example is the Banish a Cold spell.
To perform the Pet Blessing spell, start by gathering some fur or feathers from the pet. If the pet doesn't have fur or feathers, use a picture of the pet instead. A drawing of the pet is also acceptable. Now, light a white candle, and fill a small dish with some dried rosemary. Take the fur, feather or picture, and wave it through the smoke from the candle, taking care to avoid the flame.
Next, say these words out loud: "Bless our pet; he is part of our home. Bless our pet; he is not alone. Bless our pet; keep him well. Bless our pet with this spell." Place the fur or picture in the bowl with the rosemary, and leave it there until the candle burns all the way down. When the candle is burned down, take the fur or picture and put them away somewhere safe.
This spell is great for when a new pet enters the home, but children can use it at any time to protect a pet, according to Free Witchcraft Spells.