The Tale of the Silent Servant

Two kids on a farm find a scarecrow with a magic spell, and they use it. The scarecrow does whatever they order it to. At first it's great, their new servant puts up an entire fence that they were supposed to build. But they find that it has it's drawbacks when they order it to make a baseball dugout and it tears apart the new fence for wood. Things get serious when one of them accidentally orders it to kill.