Plants -  Provides links to the subcategories below.

Animals - Discusses classifying by structure and how scientists classify. Gives links to the subcategories below.

Insects - Discusses how insects are alike, antennae, mouths, eyes, thorax, abdomen, how insects grow, growing in 4 stages, growing in 3 stages, how insects survive, how insects find each other, color that protects, insects that work together, insect pests, and problems for scientists.
Note: Insects are Invertebrates.

Food Energy - Discusses carbohydrates, fats, proteins, minerals, vitamins, and the food groups.

Work & Machines - Discusses simple machines, compound machines, lifting, force, gasoline engines, diesel engines, internal combustion, gas turbine engines, electric motors, generators, and computers.

Energy Sources - Discusses the sun's energy in relation to plants and animals, solar energy, wind, water, steam, and fuels.

Matter - Discusses the 3 states of matter, changing the states of matter, facts & theories of matter, the motion of molecules, molecular attraction, using molecular attraction, heat energy, measuring heat energy, transferring heat energy, and heat to mechanical energy.
Also included is an extensive section on Chemical & Nuclear Energy: combining atoms, energy for chemical change, energy from chemical change, oxidation, energy in substances, chemical energy in living things, photosynthesis, nuclear energy, elements, energy in the nucleus, fission, mass-energy, fusion, and mass-energy transfers.

Light - Discusses what light is, light from the sun, the colors of light, how light travels, and light in different substances.

Sound - Discusses vibration, frequency, tension, sound wave, how fast sound is, controlling noise, hearing sound, and measuring the volume of sound.

Electricity - Discusses electrical energy and electrons; static electricity; electricity in the sky; steady currents of electricity; generators; electricity from fuels, nuclear fuels, chemical energy, light energy; solar batteries; measuring electrical energy, electric currents; how a switch works; switches for special jobs; feedback control; good and poor conductors; danger in a short circuit; and electromagnets and permanent magnets.

Weather - Discusses what weather is and provides links to the subcategories below.

Seasons - Discusses why the seasons change.

Gravity - Discusses what gravity is.

Geology - Discusses constructional forces and destructional forces of the earth.

Resources - Provides links to the subcategories below, and has a link to Energy Resources (located under Energy & Matter).

Conservation - Discusses soil and water conservation.

Solar System - Discusses the solar system & how it was formed, the sun, planets, moon, and tides. Gives links to the main subcategories below.

Travel - Discusses navigating in space, where space begins, launching spacecraft, to the moon & back, what's different about being in space, and provides links to the subcategories below.

Satellites - Discusses what a satellite is, how it is launched, its orbit, what keeps it in orbit, satellites getting information, collecting information about meteors, equipped to measure temperature, containing instruments to detect radiations, equipped to study the earth's magnetism, and carrying live animals.

Beyond - Discusses neighboring galaxies, more about galaxies, new findings, and changes in the universe.

Astronomy - Provides links to the subcategories below. 

Workers - Discusses the plant-nursery worker, fish & wildlife specialist, computer programmers & computer operators, chemists, weather observers, astronomers, environmental careers, cartographers (mapmakers), working with resources, geophysics, volvanologists, seismologists, paleontologists, soil conservationist, city planner, forest rangers, people who control the weather inside a large building, meteorology & meteorologists, crops & climatologists, people who study air pollution, working on the water, knowing about water, finding water, wastewater-treatment plant operator, knowing about the ocean is important in many jobs, marine biologist, chemical oceanographer, solar engineers, people who make space travel possible, and science writing.

Careers - Provides questions to help you decide if you have an aptitude for science and lists some general careers in science.