Animals

• BBC Nature: Wildlife
• National Geographic: Animals
• The Natural History Museum: Dinosaurs
• Smithsonian National Zoological Park: Animal Index
• Endangered Species
• Wildinfo.com: Wildlife Fact Sheets
• World Almanac for Kids Online: Animals

Biomes & Conservation

• Biomes of the World
• Blue Planet Biomes: Biomes of the World
• Camp Silos: From Native Prairie to Present
• Conservation Web Field Trips: Field Trip Earth
• The Dirt on Soil
• EcoKids
• Educational in Nature: Forest
• EduGreen Explore
• Mountain Adventure
• World Biomes 

Plants

• Biology4Kids
• The Great Plant Escape
• University of Illinois Schools Online
• USDA Plants Database

Earth Science

• Energy Kid's Page
• Geography4Kids
• Internet Geography
• OceanWorld
• Smithsonian: Department of Mineral Science
• USGS: Water Science for Schools

Weather

• U.S. Environmental Protection Agency: Global Warming
• Weather Wiz Kids
• Web Weather for Kids

Planets & Solar System

• Amazing Space
• Children's Museum of Indianapolis: Cosmic Quest
• NASA: Solar System Exploration
• National Geographic: Science and Space
• The Nine Planets for Kids
• Windows to the Universe

Science Experiments

• USDA for Kids
• San Francisco Exploratorium: Hands-on-Activities
• San Francisco Exploratorium: Online Activities
• San Francisco Exploratorium Snacks: Experiments
• Science Buddies
• Science Fair Central: Project Ideas
• Science Projects: PBS Kids/ZoomSci

Famous Scientists & Inventors

• Great Idea Finder: Inventor Biography
• Invention Dimension: Inventor of the Week Archives
• MIT: Inventor of the Week
• Windows to the World: People in Science
• World of Scientific Biography