Temper tantrums usually occur when the child is upset about something which can’t be effectively verbalized. The language of peace could be introduced before such an event.
A space must be allocated in each home, on what we can call a “peace place”. If one of the children (above 6 years) show temper, please encourage them to walk over to the peace place to have a dialogue with you. Our effort must also go into finding out what a younger child is attempting to communicate. It might be a movement or an opportunity. Once we find that out, we need to make an objective judgment whether that opportunity can be provided for that child or not. If yes, you can provide it with natural limits (like time or space) included. If not, explain the same to the child and tell him it is ok for him to be upset.
Give them the moral support until they come out of the period by staying with them if they cry.