Some fun ways to get kids interested in science include performing various kitchen chemistry experiments. Find a particular hobby or profession they are interested in, such as flying, and teaching them the scientific concepts behind it. Make even an everyday thing such as electricity interesting by demonstrating how it works or discussing how it was discovered or invented.
Kitchen chemistry experiments are easy to perform and are relatively safe, but are still best performed with adult supervision. Mix baking soda with vinegar, and watch the acid-base reaction. Use dissolved salt, sugar or borax, and grow crystals over a period of days. Hands-on experiments get kids involved in the science and jump start their imagination, making them curious to try other experiments or add to the ones they are performing.
If your kids like to build with blocks or create artistic structures such as clay models, show them how science and math make those structures sound or how the material from which the structure is made is created or bonded. Find resources online, in videos or in kid-friendly magazines, and read or watch them together; then, have a discussion about any questions they may have. As the seasons change, take them outside to do something fun, such as jumping into a huge pile of leaves in the fall, and talk about how the rotation of the earth around the sun affects sunlight, temperature and plant growth.