This page's description of the various kinds of radioactivity includes some discussion of the history of its discovery, illustrations, and hot links to related sites.

This page is from a comprehensive and comprehensible tutorial in physics. Schematic drawings, questions for understanding with the answerers, and links to animations are included.

Though titled for kids the information presented at this site is thorough and supported with hot links to related concepts as well as illustrations. Click on the blue Next Stop on the Tour button to continue learning.

This video segment adapted from A Science Odyssey takes a look at the scale of the atom and the tremendous amount of space between the electrons and the nucleus. If all this empty space exists in matter, how can any substance be solid?

Most non-permanent markers use inks that are made of mixtures of colored pigments and water. How does Black Magic work? Why do some black inks separate into many colors on a wet coffee filter? Why does mixing many colors of ink make black?

The amount of monitoring and adjusting that goes on in the human body at any given time is astounding. In this interactive feature every change in activity requires you to make adjustments in respiration or heart rate or energy delivery, and an adjustment to one system often changes the balance in some other system. See if you can do as good a job maintaining the harmony in this virtual body as your nervous system does in you.

This short article describes the common properties of all carbon containing compounds and points out that basis of life's molecules is carbon, thus carbon compounds are ubiquitous in living things.

These pages are set up like a self guided tutorial. Click on the next stop on the tour button at the bottom of each page to learn more about matter, states of matter and the particulate nature of matter.

This is an online interactive periodic table of the elements which includes all elements up to 118. There are several different options for viewing, such as date of discovery, electron configuration, number of neutrons, etc. Elements can also be viewed by element groups. Additional links to further information on a particular element are given in some cases. Citation information is also provided.

Though titled for kids the information presented at this site is thorough and supported with hot links to related concepts as well as illustrations. Click on the blue Next Stop on the Tour button to continue learning.

This article describes what comets are in general, some specific comets, and some astronomers associated with finding and understanding comets. Photographs are included.

This page from a comprehensive physics site, describes, defines, and illustrates electrical conductivity. Click on Resistance in the right hand navigation bar for similar information regarding conductivity's opposite, resistivity.

This animation provides a practical example of the impact of the Coriolis effect on daily life. After examining the animation, students can use a map or globe to locate where the pilots might have landed if they had followed their original flight path. They can then estimate how many miles the pilots have gone off their course. Students can also think about factors that navigators would consider when planning their flights and research the calculations used to account for the Coriolis effect. Although the resource was designed to accompany a specific Earth science textbook, it can be used without that text.

This page is from Discoveryschool.com. It has three sections. The first one, Down and Dirty, describes the various soil horizons. The second section, Field Guide, identifies some soil organisms and the third section, Soil Safari, is an animated tour of the soil beneath your feet.

This essay with images explores seed dispersal by wind and water and describes some of the many physical adaptations waterborne seeds and fruits have that allow them to traverse the world.

This short page is a concise presentation of how electricity can be generated. Hotlinks to circuits and current electricity are embedded. The left navigation bar includes links to Energy and Work, Potential and Kinetic Energy, Types of Energy, Atoms, Circuits, and Electrical Generation.

Through the process of photosynthesis, plants harness the sun's energy and in so doing make many forms of life, including human life, possible. What path does this energy follow, and how is it transferred from one type of organism to another? In this feature, adapted from Interactive NOVA: Earth, learn why 400 pounds of corn can't be converted into a 400-pound cow.

The user can vary the strength of the selection pressure, a predator, pathogen, or pollution for example, which is how change in the environment is simulated. Mutation rates can also be varied. The interaction of these two variables gives rise to adaptations, thus evolution. However, the same two variables also explain extinctions when random mutations produce traits which decrease, rather than increase fitness and/or when environmental change is so severe, a large proportion of a species is killed off in a few generations, not leaving enough individuals to repopulate before other species' outcompete the now rare species.

Article describes natural selection, its dependence on genetic variation and the role of the changing environment in natural selection.