`Air PressureBrian Cagle                    John W. Cook                               8150 S. Bishop                               Chicago IL 60620                               (312) 535-3315Objective:     The main objective of the mini-teach is to demonstrate an understanding of how air pressure works.  Students will be able to identify, construct, and      define the concept of air pressure by working in groups after experimenting with various activities on air pressure.  Students will also have a working knowledge of the different terminology used when describing the process of air pressure.                                  Activity #1: Water Fountain    Materials:     2 jars (one with the lid), 4 straws, small bucket, water, tape              Strategy:      Make two holes in the jar lid, one hole in the middle of the lid and the other near the edge.  Place one straw in the middle hole and secure both ends  of the hole with clay.  Now tape the three straws together and place one end    inside the second hole of the jar lid about an inch.  Secure both ends of this hole with clay.  Fill jar #1 without the lid about three-fourths of the way  with water.  Now fill jar #2 with the lid about 2 inches high with water and then close the lid.  Take jar #2 with the lid and turn it over so that the one straw in the middle hole is half-way in jar #1 and half-way in jar #2.While the other straws which are connected are hanging over the edge into a   small bucket.  Now observe what happens in jar #1 and jar #2. Results:    As the water from the closed lid jar #2 pours down into the small bucket    through the connected straws, the air pressure inside the jar become less as the air spreads out to take up space left by the water.  The air outside in     jar #1 is at a greater pressure than the air inside, thus forcing the water up the straw and making a fountain.                                  Activity #2: The Magic GlassMaterials:    Jar, 4"x6" index card, waterStrategy:    Fill the jar to the top with water and wet the rim slightly.  Lay the card on the top of the jar.  Hold the card firmly in place and turn the jar over.  Now take away your hand and see what happens.     Results:    The water should stay in the glass, showing that air pressure is exerted on the card from the top, the side, and the bottom as Pascal's law states.                                 Activity #3: Candle In GlassMaterials:    Shallow dish or pan, candle, matches, tall glass or flask, food coloringStrategy:    Light a candle and stand it upright in the middle of a pan and secure it with melted candle drippings.  Fill the pan half full with water.  Then add a  drop of food coloring to the water to make it more noticeable from the back of the room.  While the candle is still burning, place a narrow glass or flask over the candle.  Carefully observe the base of the container, the water level in the container, and the flame.  Record your observations.Results:    The candle will burn for a time but will eventually go out and you will see that the water rises up into the jar.  You will find out that the water will rise about one-fifth of the way up the jar.  Water rises in the container due to an imbalance in pressure.  As the gas inside the container heats and expands causing bubbling around the base.  The oxygen inside diminishes, the flame gets cooler, and so does the air resulting in a pressure drop.  Water starts to move into the container.  When the candle is extinguished, the temperature in the flask drops, causing a further reduction in pressure and a further rise in the water level.                                   Activity #4: The Power of AirMaterials:    Ruler,  2 sheets of notebook paper, 2 sheets of newspaper Strategy:    Lay the ruler on the table so about one-third of it lies over the edge.Place two sheets of notebook paper on the ruler and press against the table until the paper is flat as possible.  Now hit the overhanging portion of the ruler with your hand and try to make the paper fly into the air.  Repeat this procedure using two sheets of unfolded newspaper and record your results. Results:    The ruler should snap when placed under the newspaper, but not when placed  under the notebook paper.  The notebook paper is small enough that the ruler    can lift it without breaking.  While the newspaper has a much greater surface area than the notebook paper.  The air presses down on the sheet of newspaper,  there is a lot of air pushing down on it and this is enough to stop the paper and ruler from moving.Performance Assessments:     Through an oral evaluation and teacher observations each student will have to describe the procedure of each activity and the results of each experiment. Explaining what happens when their is an indifference in air pressure and what  caused it.Conclusion:    After experimenting with each activity, each student should have an excellent idea of how air pressure works.  While having a working knowledge of some of the key terms associated with air pressure such as: high air pressure, difference in pressure, and low air pressure.`