According to The National Center for Improving Science Education, there are nine scientific concepts that elementary school children should learn and understand. These should certainly be incorporated into the school science curriculum, but parents can, and must, also play an important role in helping their kids learn science.
These nine concepts are:
1. Organization. Science is the study of the natural world. To help them understand how things work, scientists organize and classify the objects and events they observe. For example, a hierarchy is a series which ranks each part according to some characteristic: an atom, molecule, stone, mountain, planet. Or they can be grouped based on shared characteristics: mammals, birds, reptiles, insects, etc. Elementary school children can learn the concept of organization by collecting and sorting things according to their characteristics, for example objects like rocks, leaves or flowers.
2. Cause and effect. Science seeks to explain and understand the natural world. Things happen for a reason: there is a cause for every effect. Try to point these things out to your children during everyday activities. For example, plant growth. The grass grows because there is water and light. Without those things, the grass would die.
3. Systems. A system is a group of related, interacting parts that together form an interdependent whole. In science, there are two kinds of systems. One kind is the a physical system involving matter and energy, and the way they move and react with the world and each other. The other is the system that we use to study the world, called The Scientific Method. Children can learn about systems by observing the changes in the various parts of the whole, using familiar things in their lives. For example, they can learn about equilibrium and balance by observing how an aquarium works.
4. Models. A model is something that is used to represent another thing. A model can be physical object, or a description of a thing or system. This may be hard at first for young children to understand. But you can start by drawing a picture or diagram, and comparing it to the actual object. For example, draw a picture or make a clay model of a tree, including roots, trunk, branches and leaves, and show your child how it relates to a real tree.
5. Scale. This refers to size and quantity. Playing with rulers and scales let children see that objects vary in quantity. Objects that are similar to each other can be larger or smaller, weigh more or less. For example, weigh and measure the heights of people, your family and friends. These differences will be obvious to children. There are other differences that are not obvious, but still exist and can be measured. For example, use a thermometer to measure temperature of warm and cold water, explaining that the temperature measures difference in the energy of the water.