I am now teaching Science! It has been about 7 years since I taught Science so I will be adding more sites as I come across them!

Cool Science Sites:
BrainPOP Jr - great site with cute games
BBC Schools- Primary grades - activities for ages 4-11
The Yukiest Site - great site for Science - games and info
Discovery Kids - games, videos, and more
Science Games - lots of Science games
Classify - mammals, plants, birds, and more
Fun & Games - website with a lot of Science related online games

Magnets:
Magnets and Springs - lesson about magnets, magnetic materials, and springs
Magnet Activity- choose different objects to see if they are magnetic
Quiz - information about the characteristics of magnets and springs

Forces:
Forces Lesson - information about gravity, weight & mass, balanced forces, and unbalanced forces
Forces in Motion - activity on forces in motion
Forces Quiz - information from the lesson and activity from the 2 links above
Friction Lesson - what is friction, useful friction, reducing friction, and air resistance
Friction Activity - discovering and understanding friction
Friction Quiz - information from the lesson and activity from the 2 links above

Matter:
States of Matter- game to identify characteristics of solids, liquids, and gases
Molecularium - fantastic site that explains molecules, atoms, particles and much more!
StudyJams - solids, liquids, and gases made easy from the scholastic website
Science Materials - BBC Schools which has lessons, activities, quizzes for the states of matter

Earth and Space:
StarChild- huge site with tons of links and information about the solar system
Solar System Fun - huge site with games and info from NASA
Astronaunt Adventures- huge site with different missions where students can gather information about outer space
Astronomy for Kids - huge site with information on the solar system, Sun, Moon, planets, and more
Astronomy Dictionary - terms with definitions
Comets- information and pictures about comets
More comets - few facts and two pictures
A Comet's Tail- information, games, pictures, and more
Meteoroids and Meteorites - huge site with info and pics
Meteoroid facts - quick facts and a pic
Astronauts- two pics of astronauts and some info
Space Suit - explains how the space suit works
Launch Pads - pictures of different launch pads

Moon and Phases:
Moon Phases- from StarChild website and explains the phases of the moon
Diagram of Phases - from the website above but gives a different diagram about the moon's phases
Sun and Moon Data- get complete Sun and Moon data from the USNO website
Moon Video - shows the phases of the moon

Health and Body:
Health and Growth - information about healthy eating habits
Health Activity - learning how different activities will change your heart beats per minute
Health Quiz - information that was discussed in the lesson and activity above

Land Forms:
Illustrated Glossary - List of land forms and bodies of water from Enchanted Learning
Understanding Landforms - examining the Earth's layers, rocks, and landforms
Interactive Map - Landforms of the United States
Landforms - landforms of the Earth - pictures and information
Types of Land- choose a type of land from the drop down menu and see it on a map with facts
Landforms/Habitats - huge site with many links about habitats and landforms
Web Geography for kids - nice site with many links

Rocks:
Rocks and Soils - lesson, activity, and quiz about the characteristics of rocks

Weather:
Weather Wiz Kids - huge site from an ABC meteorologist
Weather Channel for Kids - the weather channel's web site that is focused on kids - information, games, and cool clips
Web weather - info on weather and its elements
Water Cycle Lesson - information about the water cycle and printable worksheets
Water Cycle Site - tons of links and information about the water cycle
Interactive Water Cycle - cool animation with great information