Product Description:
#1638 K-8 Science - How Levers Work (Run time 5 min.) DVD $29.95
A thin ruler can lift a heavy paint can. How? Watch Bob Symes demonstrate the power of the lever, how it works, and how moving the position of the fulcrum changes its ability to work. (5 minutes)
#1639 K-8 Science - What Is a Wedge? (Run time 4 min.) DVD $29.95
We are surrounded by wedges that help us every day-ramps, staircases, knife blades. Wedges exert force in two directions: forward and up. Bob Symes demonstrates the difference in action between a thin wedge (it travels a long way forward to achieve a little lift), and a thick wedge (it can lift an object and travel only a short distance). (4 minutes)
#1640 K-8 Science - How Gears Work (Run time 8 min.) DVD $29.95
Bob Symes demystifies the subject of gears. He explains how thinking about gears as "round wedges" reveals why a large gear wheel spins slowly but produces a lot of power, while a small gear wheel spins quickly but produces little power. (8 minutes)
#1641 K-8 Science - How a Screw Works (Run time 7 min.) DVD $29.95
Compare the amount of work needed to remove a nail from a board with the amount of force required to remove a screw. Screws and nails are really different simple machines; the screw is a wedge wrapped around a cylinder and exerts force in several directions just as an ordinary wedge does. (7 minutes)
#1642 K-8 Science - Why Lightning Is Dangerous (Run time 7 min.) DVD $29.95
Everyone knows what a lightning rod is, but how does it work? Bob Symes creates lightning in his laboratory and reveals the secret of the lightning rod-it doesn't conduct the electrical charge, it disperses it. (7 minutes)
#1643 K-8 Science - Why It Rains (Run time 6 min.) DVD $29.95
Bob Symes makes rain in his kitchen. Real rain occurs for the same reason that steam, when it hits a cold windowpane, will turn to water droplets. The experiment makes clear the roles of water vapor and temperature in making rain. (6 minutes)
#1644 K-8 Science - How to Recognize Plant Fingerprints (Run time 7 min.) DVD $29.95
Like human beings, plants have unique characteristics that identify them as belonging to one specific group. Bob Symes takes a walk in the woods, his trusty nature guide in hand, and shows us how to recognize plant "fingerprints" and use them to identify trees, mushrooms, and other plants. (7 minutes)
#1645 K-8 Science - How to Measure Time (Run time 7 min.) DVD $29.95
How was time measured before the clock was invented? In fact, there are many ways of measuring time and, if you think about them, many are familiar to us-the sundial, the egg timer. Bob Symes explains how we can use one process (such as burning a candle marked at regular intervals) to measure another (such as the passage of time). (7 minutes)
#1646 K-8 Science - How to Make Pictures Move (Run time 8 min.) DVD $29.95
Motion pictures are just that-pictures in motion. The magic of making pictures move is demonstrated by a simple experiment that children will find fascinating and fun to do. Bob Symes explains that a stick figure, drawn in a series in which slight changes in position occur in each drawing, will appear to move across the page. Why? Because your eye can see only a limited number of distinct images over a specific period of time. (8 minutes)
#1648 K-8 Science - How a Chimney Works (Run time 9 min.) DVD $29.95
The smoke from a campfire will travel in any direction, but why does the smoke in a fireplace only travel up the chimney? Bob Symes answers this question by explaining the principle of the air pump. Hot air rises; as the air in the fireplace is warmed it travels up the chimney and spills out the top. The warm air that leaves the fireplace is replaced by cold air from the room. Our chimney "air pump" only works in one direction. (9 minutes)
#1650 K-8 Science - How a Saw Cuts (Run time 6 min.) DVD $29.95
Look very closely at the cutting edge of a saw and you will see that it is very different from the cutting edge of a knife. The saw blade is made of a series of "teeth" or tiny chisels. Each chisel is set at an angle diagonally opposing the one before it. This is called the set of the saw. Bob Symes demonstrates why the saw needs these angled chisels and how they work together to make cutting woods or metal easy. (6 minutes)
#1651 K-8 Science - How Candles Work (Run time 9 min.) DVD $29.95
Light a piece of string and the end will smolder, perhaps blaze for a moment, and then go out. If a candle is simply a wick (like a piece of string) surrounded by wax (or some other fuel), how does it continue to burn with a steady flame? While demonstrating how to make candles, Bob Symes explains capillarity and relates this concept to the wick and fuel of the candle. (9 minutes)
#1652 K-8 Science - How Television Works (Run time 6 min.) DVD $29.95
Peek inside a television set with Bob Symes while he explains the basic principles that make it work. A beam of electrons will travel in a straight line inside an airless (vacuum) tube; when the beam hits a fluorescent screen it creates a glowing spot. A magnet placed close to the beam will make it move. Our television sets have magnets that are controlled by signals sent from transmitters; these magnets change the positions and the brightness of the electron beam. These simple principles and a little electrical wizardry make the electron images on our TV sets move so fast that they appear to be moving pictures. (6 minutes)
#1653 K-8 Science - How Speedometers Work (Run time 8 min.) DVD $29.95
Cars, motorcycles, and bicycles use speedometers to measure their rate of speed, but how do they work? Bob Symes looks inside an ordinary bicycle speedometer and explains how a rotating magnet and a metal cup make the speedometer's needle move. (8 minutes)
#1654 K-8 Science - How Telephones Work (Run time 7 min.) DVD $29.95
We speak into the telephone; we hear the voice of the caller, but how do the voices travel from one telephone to the other? Bob Symes opens up a telephone receiver to find the answer. A microphone made of loosely packed carbon granules changes the electricity that passes through; the electricity moves a metal plate (the diaphragm); the density of the carbon granules depends on the pressure of the sound reaching them. (7 minutes)
#1655 K-8 Science - What Is Safety Glass? (Run time 10 min.) DVD $29.95
Safety glass, the kind of glass used for car windshields, shatters into tiny crystals when it breaks. What makes this glass different from ordinary glass that breaks into sharp splinters? Bob Symes uncovers the secret of the "glass sandwich" in his laboratory. Safety glass is given its special properties when it is quick-cooled so that the outside layer of glass hardens while the inside remains slightly softer. When the hard skin of the safety glass breaks, this not-quite-hardened center expands and crystallizes. (10 minutes)
#1656 K-8 Science - How Light Changes Color (Run time 9 min.) DVD $29.95
What produces color, and why does a color look different when viewed through lenses of different colors? Bob Symes investigates the mysteries of color with several simple experiments. By spinning a disk that has been painted with equal segments of blue, yellow, and red, he makes the colors disappear so that the spinning disk looks white. Then Bob explores the labels on various cans of paint, first in ordinary light, and then under a red, blue, and yellow light. (9 minutes)
#1657 K-8 Science - How a Photograph Is Made (Run time 8 min.) DVD $29.95
Using everyday examples (such as sunburn) and demonstrations with ordinary materials, Bob Symes explains the principle of photosensitivity. He points out the different reactions substances have to light, and then continues with a discussion of chemical reaction in the presence of light. This leads to a look at photography. (8 minutes)
#1658 K-8 Science - How Lenses Work (Run time 8 min.) DVD $29.95
Many people wear glasses to help them see, but how do the lenses in the glasses work? Bob Symes demonstrates the differences in the images produced by flat, convex, and concave lenses. He shows how a lens bends light according to the thickness and direction of its curve. (8 minutes)
#1659 K-8 Science - How Pins Float on Water (Run time 8 min.) DVD $29.95
An ordinary straight pin is heavier than a piece of tissue paper. Why does the paper sink to the bottom of a tank of water while the straight pin floats on top? Surface tension is the answer, and Bob Symes illustrates this principle with several easily repeatable experiments. (8 minutes)
#1660 K-8 Science - How Planes Fly (Run time 6 min.) DVD $29.95
The Wright Brothers discovered the secret of heavier-than-air flight, and Bob Symes explains just how airplanes stay up. The simple model of an airplane wing demonstrates the importance of its shape (rounded on top and slightly concave underneath) and its position (or attitude). When both characteristics are present, an air current passing over the wing will create pressure on the undersurface and a partial vacuum on the top surface. This produces lift. (6 minutes)
#1661 K-8 Science - What Is Air Pressure? (Run time 6 min.) DVD $29.95
How can air crush a tin can? Bob Symes reveals the power of air pressure through a simple experiment with an ordinary tin can that is heated and then sealed tight. As the tin can cools, the sides collapse. (6 minutes)
#1662 K-8 Science - How Ships Float (Run time 8 min.) DVD $29.95
This program is an introduction to Archimedes and his principle of water displacement. An ordinary brick and a piece of wood of about the same size are put into a tank of water. The brick sinks to the bottom, but the wood floats. Why? Bob Symes explains that in order to float, the water an object displaces must weigh more than the object itself. Therefore, a ship, which is hollow, displaces more water than the ship itself weighs. (8 minutes)
#1663 K-8 Science - What Happens When Water Freezes? (Run time 5 min.) DVD $29.95
Bob Symes explains burst water pipes and icebergs at the same time; they share the same scientific principle. Water expands when it freezes, a fact proven by Bob's freezer and some sample containers of water that have been left inside. When a piece of ice is put into a tank of water, it floats, but only about 1/10th of it sits above the water-the tip of the iceberg! (5 minutes)
#1664 K-8 Science - What Is Water Pressure (Run time 6 min.) DVD $29.95
Everyone has felt their ears pop under water, but why does this happen? Bob Symes explains the principle of water pressure and demonstrates that the amount of pressure depends on the depth of the water, not the quantity. (6 minutes)
#1665 K-8 Science - How to Float on Steam (Run time 5 min.) DVD $29.95
Heat a pot of water and the water boils away as steam. Heat a frying pan and then put a drop of water on the hot surface. Why does it "dance" over the surface instead of boiling away? Bob Symes discusses the "skin of steam" that surrounds the water droplets, and how this same scientific principle works to protect people from burns. (5 minutes)
#1666 K-8 Science - What Magnets Do (Run time 7 min.) DVD $29.95
A compass needle points North because the Earth has a magnetic force that attracts the metal in the needle. Bob Symes shows what happens to the compass needle if a wire with an electric current is placed next to the compass. He proves that this principle works backwards as well as forwards; electricity can be generated by pushing a magnet through a wire coil. (7 minutes)
#1667 K-8 Science - Why Light Bulbs Glow (Run time 6 min.) DVD $29.95
Bob Symes proves that air (oxygen) must be present for an object to burn. A light bulb is a glass "envelope" surrounding a vacuum. When electricity passes through the wires inside the bulb, the wires get hot and glow, but they do not burn because there isn't any air in the bulb. (6 minutes)
#1668 K-8 Science - How Batteries Work (Run time 7 min.) DVD $29.95
Although batteries may look complicated, they are as simple as lemons. Bob Symes uses this fruit as the source of electrolytes-a basic component of all batteries. He attaches two dissimilar metal rods (one zinc, one copper) to a lemon and then measures the electricity produced. (7 minutes)
#1647 K-8 Science - Why Every Action Has a Reaction (Run time 5 min.) DVD $49.95
Fill a balloon with air, and then release it. Why does it fly away? A jet engine and the balloon operate on the same scientific principle. Bob Symes explains pressure using the balloon as an example, and demonstrates how the release of pressure in one direction will force the balloon to move in the opposite direction. (5 minutes)
#10010 K-8 Science - Weather: An Introduction (Run time 18 min.) DVD $59.95
Where on Earth does the temperature drop to -128 degrees Fahrenheit? What is a wind farm? And how does rain look from an ant's perspective? Combining remarkable time-lapse and slow-motion photography with news footage and diagrams, this program provides a thorough overview of the causes and effects of the Earth's weather. Sections one through three present temperature, wind, and precipitation, while sections four through seven focus on weather measurement, the impact of weather, the formation of clouds and the clues they give about future weather conditions, and the effects of extreme heat and cold, hurricanes, and tornadoes. Appropriate for middle school. (18 minutes)
#1696 K-8 Science - The Way Things Work (Run time min.) DVD $918.5
Bob Symes, noted British science broadcaster and inventor extraordinaire, looks at everyday objects and events, and explains the basic scientific principle or law involved. He backs up all he says with clear and interesting experiments. 30-part series, 4-10 minutes each.
