To convey data from one point to another we need to represent the data by means of a signal. We can think of a signal as a deliberate variation in some property of the medium used to convey the data. Some examples are:

an electrical voltage travelling along copper wires between your telephone and the local exchange;

pulses of light (though we might not be able to see them) in a fibreoptic cable;

the radio emissions t
Art History in a Hurry  Mona Lisa
This is a fascinating video about this famous painting. Wouldn't you like to know why she has no eyebrows? (02:17)
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Medicine I
This course teaches the dental student basic medicine skills, from History Taking to the Physical Examination. It provides concise practical information about patient assessment, symptoms and signs of common diseases, laboratory tests, and pharmacology and prescription writing.
Problem Solving for Immunization Programs
Countries around the world  even those at war  are collaborating to ensure that children under the age of five don't die from diseases for which vaccines are available. In the past twenty years, global vaccine coverage has surpassed eighty percent, and a second disease, polio, is nearly eradicated. In the United States, coverage rates are even higher, and vaccinepreventable diseases are now rare. Never have so many resources been focused on immunization  yet problems remain. Additional, high
Fun Food Stuff
The University of Wisconsin Biotechnology Center provides this Web site to help teachers introduce their students to the principles of biotechnology. Many of the activities use food as the experimental medium, and are easy to carry out either in the classroom or at home. By choosing the Every Demo an Experiment link, a number of other applicable biotechnology outreach materials can be found, including additional resources for teachers.
Middle School Portal: Math and Science Pathways (MSP2)
This is a collection of over 20 fun and challenging math activities created by Cynthia Lanius, the executive director of the Center for Excellence and Equity in Education at Rice University. The activities range in level from grade school to adult. Many of these lessons are designed to be used in the classroom or at home with a teacher or parent leading the way. However, students can perform these activities on their own as well. Graphing, calendarrelated algebra, money making problems, and fra
Middle School Portal: Math and Science Pathways (MSP2)
This is one of the best online resources about fractals, and is meant to support a first course in fractal geometry for students without especially strong mathematical preparation. The site is incredibly deep, providing everything from the most basic definitions and nontechnical discussions to involved mathematical formulations. Interactive Java applets, downloadable software for the PC and Macintosh, and laboratory activities are also presented. A particularly interesting section of the site e
Middle School Portal: Math and Science Pathways (MSP2)
Six days a week, a new math problem is posted on this Web site to intrigue and challenge grade school students. Each Daily Brain has a different theme, considering some mathematical perspective of science, history, geography, and more. After solving the problem, or for a little help, students can look at a stepbystep solution that is also posted online. All old Daily Brains are kept in an archive, and as of May 2003, they numbered around 400. The problems are mostly intended for students betwe
Middle School Portal: Math and Science Pathways (MSP2)
Located at the University of Wales, the Centre for the Popularisation of Mathematics brings a more artistic side to the often plainly presented subject. Several online exhibits and galleries illustrate sculptures and knots that have a basis in math. One of the most interesting and famous mathematical sculptures is the Mobius Band. The centre gives a description of the Mobius Band and its significance, as well as instructions on how to create one and interesting experiments to try. Many other scu
Middle School Portal: Math and Science Pathways (MSP2)
M.C. Escher is a widely known and popular artist whose work depicts complex, and often impossible, geometrical patterns. This Web site examines the mathematics behind his drawings. Many examples of Escher's work are given, illustrating mathematical principles such as the shape and the logic of space. Tessellations and polyhedra are common building blocks of the drawings. It is quite interesting to see how basic designs are transformed into the intricacies depicted by Escher. The material is cert
Office for Mathematics, Science and Technology Education
The Office for Mathematics, Science, and Technology Education at the University of Illinois at UrbanaChampaign has an impressive collection of Java lessons and curriculum resources for learning about these topics. The office was established to serve as a modelbuilder for innovative, standardsbased, technologyintensive mathematics and science instruction at the K16 levels. Most of the lessons focus on geometry, statistics, or algebra; but there are also some that cover science concepts. The
Middle School Portal: Math and Science Pathways (MSP2)
This virtual manipulative with an interactive threecircle Venn diagram can be used to model set operations for union, intersection, and subset. For each statement, the student uses an onscreen paint function to find and highlight the region that is the solution. The student can click a button to find out if his or her solution is correct. In addition to the manipulative, there are 13 progressively more difficult logic statements to challenge the student. Instructions for use and a link to the N
Middle School Portal: Math and Science Pathways (MSP2)
This manipulative offers an interactive version of the classic logic game of the same name. In this version, the student plays against the computer and has eight chances to guess the colored pattern of four pegs. The student may select to play with a pattern consisting of two to six colors. The site includes instructions for using the applet, a lesson plan, and information for teachers and parents. There is also a link to the National Council of Teachers of Mathematics (NCTM) Standard for Number
Middle School Portal: Math and Science Pathways (MSP2)
Using this online activity, students explore the meaning of probability using the pigeonhole principle. The initial question asks students to determine the probability that someone who is not paying attention to what she is doing can put checks into the correct envelopes. The activity is one of 80 mathematical challenges featured on the Figure This! web site, where realworld uses of mathematics are emphasized. The solution hint suggests experimenting with the possible outcomes with checks a, b,
Middle School Portal: Math and Science Pathways (MSP2)
In this online activity, students analyze predictions made by sportswriters about which basketball teams will win to determine which teams are playing each other. The Getting Started link describes how to set up a table to organize the given information. The activity is one of 80 mathematical challenges featured on the Figure This! web site, where realworld uses of mathematics are emphasized. The solution illustrates and explains three different ways to successfully organize information, includ
Middle School Portal: Math and Science Pathways (MSP2)
This online challenge activity introduces a giftcounting problem that requires students to organize information in a table and then to draw conclusions. The importance of organizing information for decision making is noted for census takers, librarians, and demographers. The activity is one of 80 mathematical challenges featured on the Figure This! web site, where realworld uses of mathematics are emphasized. The solution hint suggests how to organize a useful table. Related questions ask stud
Middle School Portal: Math and Science Pathways (MSP2)
This online activity offers students a chance to analyze data stated as percentages to draw conclusions about the similarity of five archeological sites. Students analyze the data by making a table of the differences for each pair of sites by subtracting the smaller percentage from the larger for each of five types of evidence. The activity is one of 80 mathematical challenges featured on the Figure This! web site, where realworld uses of mathematics are emphasized. The activity features a solu
Middle School Portal: Math and Science Pathways (MSP2)
This online activity offers students a chance to compare soda prices from two stores using data displayed on a scatter plot graph. Students are shown how the line y = x can be used to analyze the data and draw a conclusion. The activity is one of 80 mathematical challenges featured on the Figure This! web site, where realworld uses of mathematics are emphasized. The activity contains a solution hint, two different ways to find the solution, questions related to analyzing similar data from other
Middle School Portal: Math and Science Pathways (MSP2)
With this online activity, students explore the classic mathematics mapcoloring question known as the fourcolor problem. Students must determine the minimum number of colors needed to color a map so that entities sharing a border have different colors. Initially, students investigate the minimum number of colors necessary to color a map of states west of the Mississippi River. The activity's Getting Started section suggests coloring the states in a specific order. The Solution page uses odd an