Meiosis is important in assuring genetic diversity in sexual reproduction. Use this interactive animation to follow Meiosis I (reduction division) and Meiosis II in a continuous sequence or stop at any stage and review critical events.

This animation demonstrates the stages of mitosis in an animal cell. Use the control buttons in the upper left to run the complete animation. Click on any intermediate stage (for example, Anaphase), and see a representative still frame.

Try your hand at assembling the following animal cell jigsaw puzzle created with an image from CELLS alive! This puzzle is 32 pieces and generally takes a few minutes to solve. Have fun!

Students work step-by-step through the generation of a different Hilbert-like Curve (a fractal made from deforming a line by bending it), allowing them to explore number patterns in sequences and geometric properties of fractals.

This is a great site to learn about apoptosis. It includes pictures, information, and links to other great sites on apoptosis. There is also a video that is available for download.

Try your hand at assembling the following bacteria jigsaw puzzle created with a Streptococcus image from CELLS alive! This puzzle is 32 pieces and generally takes a few minutes to solve.

Try this fun problem! In any group of six people, what is the probability that everyone was born in different months?

Welcome to the CELLS alive BioCams. In these BioCams, you will get to learn about cancer and bacteria cells. However, these are a bit different from "livecams" you might find elsewhere on the web - these repeat at daily or shorter intervals in order to convey information on biological rhythms.

This cell crossword puzzle uses vocabulary from CELLS alive! If you have trouble, use the "Search this Site" engine in the lefthand menu.

During development from stem to fully differentiated, cells in the body alternately divide (mitosis) and "appear" to be resting (interphase). This sequence of activities exhibited by cells is called the cell cycle. Watch this animation to learn more about each of the stages in the cell cycle: interphase, gap 0, gap 1, S Phase, gap 2, and M phase.

This cell structure crossword puzzle uses vocabulary from CELLS alive! If you have trouble and need a hint, use the "Search this Site" engine in the lefthand menu. Good Luck!

This animation depicts how dissolved minerals carried by water are deposited between grains, forming a natural cement that holds the sediments together.

Do you have a big decimals test coming up? Or are you studying for your standardized math test? This site is both fun and helpful! On this site you can review the following topics: place values of decimals, how to read decimals, expanded notation for decimals, and how to convert fractions into decimals. On this site you can also review how to add, subtract, multiply, and divide decimals. You will also learn about terminating and repeating decimals.

The Decimals Cruncher game will help you learn about decimal operations! You can choose to practice adding, subtracting, multiplying, or dividing. You can also pick how hard the game is. The game has 4 levels: easy, medium, hard, and killer. The Decimals Cruncher will keep track of your score. When you switch to a new operation (addition, subtraction, multiplication, or division), your score will start over again.

Students play a generalized version of connect four, gaining the chance to place a piece after simplifying fractions, converting fractions to decimals and percentages, and answering algebra questions involving fractions. Choose difficulty level, question types, and time. Fraction Four is one of the Interactivate assessment games.

Test your fraction skills by answering questions. This quiz asks you to simplify fractions, convert fractions to decimals and percentages, and answer algebra questions involving fractions. Choose difficulty level, question types, and time. Fraction Quiz is one of the Interactivate assessment quizzes.

Looking for a fun way to learn about fractions? Playing this fraction game will help you to learn all about them. To play the game, you simply click on the target type of fraction while avoiding the others. The game includes three rounds and each round has a different target. The targets include: mixed numbers, fractions that are greater than or equal to one, and fractions that are less than one-half. Your goal is to complete each round in the shortest amount of time possible.

Watch this short video clip to learn more about the rock layers of the Grand Canyon. This video discusses the two sandstone formations that comprise the uppermost part of the canyon. The video also discusses how the two sandstone layers were formed.

How do earthquakes work? Learn more about earthquakes, faults, P-waves, and S-waves in this HowStuffWorks video.