Spend time outside exploring and observing your physical environment. Even cities have parks with topography and lakes. Check out your state's geological survey Website for educational resources, and learn what your house is sitting on and where your water comes from. Spend days exploring beaches, mountains and rivers. Take a hike or bike the trails. Keep track of the weather for your area.
Benefits: Develops observational abilities. Recycle! Conserve! Organize a recycling center at home (paper, cans, bottles, bags). Conserve water and observe restrictions. Educate kids about conserving natural resources, limiting the amount of trash buried in landfills or burned, and disposing of hazardous waste properly. Take them with you to the recycling center (if you don't have a regular pickup). Give old computers and electronics to recycling companies or schools. Participate in local beach or park cleanups.
Benefits: Cultivates conservation, accountability and responsibility. Plant a garden, even using pots on an apartment balcony. Experiment with different soils and watering schedules. Compost vegetable scraps, grass clippings and leaves. Collect acorns and pine cones for art projects. Go to U-pick farms where kids can pick berries, apples, vegetables and pumpkins. Show them how things grow (and where food really comes from).
Benefits: Teaches that science is fun and practical.