Before introducing the laws themselves, explore the basic concepts and definitions used in the statement of Newton's laws. Explain what force is and if the word has the same meaning in science as in everyday life. In science, force is a pull or a push that can change the motion of a thing - make it move faster or slow it down. Also explain acceleration and inertia. Use demonstrations such as pulling a tablecloth out from under a dish or pulling a card out from under a coin to illustrate inertia.
According to Newton's first law of motion, a thing stays at rest or keeps moving at the same speed unless a force makes it change its motion. This tendency of a thing to stay as it is is called inertia. Inertia of rest is easy for children to understand since things generally don't move of their own accord. Inertia of motion is harder to explain. In the real world moving things slow down and stop even though there is no obvious force. To clarify how Newton's first law works for things in motion, explain that friction is a force. Do an experiment to show how an object moves differently on a rough surface compared to a smooth surface.
According to Newton's second law of motion, force applied to an object makes it move faster. In fact, the greater the force, the faster the object speeds up. To make a bigger object speed up at the same rate, you need a bigger force. Even without introducing the equation Force = Mass x Acceleration, you can communicate the essence of the second law of motion by doing experiments to demonstrate the concepts mentioned above. For example, you can have the children hit balls of different sizes with bats and note how hard they are hitting and how fast the ball moves.
Newton's third law states that every action has an equal and opposite reaction. Give examples where a student can directly experience this. If a child hits a desk hard, he will feel a strong force on his hand. Do experiments to show how Newton's third law can be used to launch something into motion. For example, let air out of an inflated balloon and explain how this is similar to the way rockets are launched upwards by pushing hot gases out and downwards.