Activity number 1 - an experiment Purpose - To see the effect of the earth's tilt Materials - a globe or map of the earth - a small flashlight. Observations Method The shape and the intensity of the light changed In a darkened classroom, have your students shine when they shone it on the Tropic of Cancer because the light directly down on the equator. Is the light the beam hit the surface at an angle and spread over bright? Can you see its outline clearly? a larger area. Keeping the flashlight at the same height and over Conclusions the equator, have them tilt the flashlight so that it The earth's tilt affects the strength of the sun's rays shines on the Tropic of Cancer, north of the equator. at different points on the earth's surface. Does the area of light look like the one which was created when they shone the flashlight directly on the equator? Does the light cover a larger area? What does the shape of the light look like? Are some parts of the area lit by the flashlight brighter than others? Adapted from Brenda Wyman, Weather. Investigations in Science Series. (Cypress Calf. Creative Teaching Press Inc., 1995) P.15. Activities / 8-1 Activity number 2 - an experiment Purpose - To show that air has weight Materials - two balloons - tape - ruler or yardstick - string - pin Method Have your students inflate the balloons until they are the same size; then tie them shut. Have them put a piece of tape on one of the balloons near the opening, and use 2 pieces of string to tie one balloon to each end of the ruler or yard stick. Have them tie another piece of string around the centre of the ruler and hang it up so that the two balloons are balanced and they do not rub against a wall. Take the pin and make a small hole in the tape on the one balloon. When you step away, make sure the two balloons are still balanced. Observations The balance changes as the air in the one balloon leaked out and the balloon became lighter. Conclusions - Air has weight. Adapted from the Internet site http://unitedlearning.com Activities / 8-2 Activity number 3 - Building a weather instrument Purpose - This project explains how to make a barometer to show changes in air pressure Materials Points of discussion - Empty glass container or soup can The piece of the balloon that is stretched across the - Elastic band jar will act as a membrane. When the air pressure - Glue outside the jar rises, it will push down on the - Adhesive tape balloon, forcing it slightly into the jar. This, in turn, will cause the end of the straw to rise. Similarly, - Balloon when the air pressure outside falls, the air pressure - Drinking straw in the jar will be greater than the air pressure around - Index card about 8 cm by 13 cm it forcing the balloon to bulge slightly. This will (3 inches by 5 inches) cause the end of the straw to drop. Method You can chart the position of the straw against the reference marks on the card each day. This will not Cut a piece out of the balloon large enough to cover give you a numeric reading but it will tell you the top of the glass jar or soup can. whether the air pressure is rising or falling. The Stretch that piece of the balloon tightly over the top pressure trend is an important tool in forecasting. of the jar or can and secure it in place with the Please remember to keep your barometer away from elastic band. sources of heat such as radiators and sunny window Cut the straw so that it is about 10 centimetres long ledges. If it is close to a source of heat, then your and trim one end to a point. barometer will act more as a thermometer, with the air inside expanding and contracting to reflect With the sharpened end pointing out, lay the straw changes in temperature, not pressure. on the balloon with the flat end at about the centre of the balloon. Glue the straw in place. Draw reference marks on one of the long edges of the card at roughly half-centimetre intervals. Tape the opposite (unmarked) side of the card to the jar, with the narrow end of the rectangular card extending above the jar top and the marked edge just behind the straw. The marked edge should stick out so that the sharpened end of the straw points to the reference marks. Activities / 8-3 Activity number 4 - an experiment Purpose - To show that air exerts pressure Materials Method - Part two - A thin rectangular board, for example a strip of thin Ask your students what will happen if you slowly push plywood or paneling which is about a half metre long down on the protruding board. Then push down on the and 8 to 10 centimetres wide board slowly. What happens to the paper this time? - One full-size newspaper Observation - Ruler - Paper and pencils The paper slowly rises off the table. Method - Part one Conclusion Place the board on the table with slightly less than one Air exerts pressure on all surfaces that it touches. half of the board hanging over the edge. Open the When an air space is created under the paper, the newspaper and lay it flat over the section of the board pressure exerted by that air counteracts the pressure on the table. Ask your students what they think will from above and the paper is no longer held in place. happen to the paper if you strike the part of the board that is hanging off the table. Then strike the protruding part of the board as hard as you can. What happens to the paper? Does it move? Does the board flip up as some of your students thought it would? Final Activity: Have your students calculate how Observations much pressure was being exerted on the paper inThey part can one measure of this experiment. The paper remained in place. the length and width of the newspaper in centimetres, then multiply the 2 measurementsAsk them to Conclusion get the surface area. how many kilograms of air are The paper did not move because the air pressure that is pressing down on that sheet of newspaper using the average exerted downward held it in place. Since the paper is sea level pressure of 1 flat against the table, there is no air beneath the paper kilogram per square centimetre. to counteract the pressure from above. If you hit hard enough, the board will break. Martha Suarez, Stephen F. Austin, University Nacogdoches, TES Course, 1994 Activities / 8-4 Activity number 5 - Building a weather instrument Purpose - An anemometer measures the speed of the wind. You can make one easily with a ping pong ball and the protractor from your math set Materials Angle Kilometres per hour 0 - Needle 90 0 850 9 - Thread 800 13 - Ping pong ball 750 16 0 - Protractor 70 19 650 22 Method 600 24 550 26 Cut a piece of thread about 20 centimetres long. Thread 500 29 the needle and tie a large knot in the end of the thread. 450 32 400 34 Stick the needle into one side of the ping pong ball 350 38 and out the opposite side. Draw the thread through 300 42 until the knot at the other end stops the thread 250 46 from moving. 200 52 Tie the thread to the centre of the straight base of the protractor so that the ball hangs below the arc of the protractor which has the angles marked on it. If the protractor is held level, where there is no wind, then the ball will hold the thread over the 90O mark. Take the protractor outside. Hold it level and parallel to the wind. The wind will blow the ball and when it does, note the position of the thread on the protractor. Record the angle that the ball has been blown and use the chart to convert the angle to a wind speed. Activities / 8-5 Activity number 6 - Building a weather instrument Purpose - To make a wind streamer for use as a wind vane to discover from which direction the wind is blowing Materials 7. Now repeat this step until all 4 holes have streamers in them. - large paper plate - magic marker 8. Write in capital letters N(north), E(east), S(south), and W(west) next to each hole. - scissors - crepe paper streamers 9. Paste or tape the Sky Watcher logo in the middle on the top of the plate. - coloured pencils or felt pens - paste or tape To use the wind streamer, take your class outside and have each team do the following (you may want to take - the Sky Watchers logo, Cloudy, on the next page a compass): Note: if you have your students working in teams, you 1. Find an area outside where there are no buildings or may want to photocopy Cloudy and have each team make woods to interfere with the wind, a hill for instance a wind streamer. or a playing field. Method 2. Hold the wind streamer in front of you so that the plate is parallel with the ground and your thumb is To make the wind streamer, have each team follow these on top of the plate near the letter S. steps: 3. Turn the plate so that the N on your wind streamer 1. Cut out the Sky Watchers logo along the black circle is facing north.