In this section various scientific experiments are suggested for classroom activities. In order to develop good scientific habits, a certain degree of structure should be introduced to the students regarding the execution of the experiments. What follows is a brief description of the scientific method. The scientific method is a good model for proper execution of experiments; it encourages problem solving, and thorough notation and analysis of experimental results. (These steps need not necessarily be written; they can be done orally with younger students.)
Before each experiment, the students should form a specific question that they plan to answer through the experiment. If applicable, they should research information pertaining to their question. They should then make a hypothesis about what they expect to happen and decide on a procedure to answer their original question. They can write down their ideas or discuss them with their classmates. Have the students make and record careful observations throughout the course of the experiment; a chart for the children to fill in is a good idea. The students can then draw conclusions, based on their findings. Finally, hold a class discussion to share results.
The first exercise provides a good way to familiarize students with the scientific method.
Exploring the world with the scientific method
Using the scientific method (as described above), solve a classroom mystery, where students will have to find clues, make predictions, test hypotheses, experiment, observe and form conclusions. For example, the class could be presented with a glass of salty Kool-Aid, a trail of salt or sugar by the sink and someone's hat left nearby. The students would then have to investigate: Who made it? Where were the ingredients stored? Was it deliberate or accidental?
Here is another experiment to help children practise the scientific method: Into a clear container, put equal amounts of water and vinegar (100 mL each). Add a few raisins to the container. Record what happens. Now add 15 mL baking soda, and record any observations as you examine the container contents for several minutes. Repeat the experiment with popcorn or peanuts, rather than raisins, and compare the results. Upon mixing the baking soda and vinegar, the bubbles that float the raisins to the surface are bubbles of carbon dioxide gas produced by the reaction between acetic acid (vinegar) and sodium bicarbonate (baking soda). Once a raisin rises to the surface of the liquid, the carbon dioxide bubbles escape from the solution and the raisin falls until more carbon dioxide forms on the surface.
To further investigate carbon dioxide gas, add about 35 mL more baking soda to the container. (Make sure that your container is large enough so that the solution does not reach the brim.) After the reaction has been allowed to proceed for a few minutes, a layer of carbon dioxide will have formed on the surface of the liquid. It will not mix with the air in the room because carbon dioxide is heavier than air. To prove that the carbon dioxide is present, slightly tip the container over a lit candle. The flame should be extinguished. Make sure that you don’t pour the liquid over the flame; you only want to pour out a layer of gas that is sitting on the surface of the liquid. The reason the flame goes out is because the candle needs oxygen to burn. Once the carbon dioxide smothers the candle, there is no longer any oxygen present to feed the flame.
Kitchen chemistry
Ask the students to bring in an item from their kitchen (food, paper towel, string, etc.). Conduct experiments in class to test for the presence of starch in the items. This is done by dropping a few drops of iodine on the surface of the food or paper. If the iodine produces a blue-black or brown colour, then the object contains starch. The iodine can be purchased in drugstores; ask for "red tincture of iodine." If possible, test bananas at different stages of ripeness. As a banana ripens, its starch content is gradually converted to sugar. Therefore, the iodine will have different results with an unripe banana than with a ripe one. Try it!
Electric paths
In class, test various objects and materials for electrical conductivity. Try rocks, a spoon, the graphite of a pencil, a crayon, a magnet or a glass of tap water. Note that distilled (pure) water does not conduct electricity, while tap water containing impurities does. An easy way to test for electrical conductivity is to set up a simple circuit: Attach an insulated wire to a small light bulb and connect the other end of the wire to a battery. Connect one end of a second wire to the battery, and one end of a third wire to the light bulb. As a control, touch the free ends of the two wires together to make sure that current flows through the circuit and the light bulb lights. Then touch the free ends of both wires to the object being tested, completing the circuit. If the bulb lights up (even faintly), then the object is an electrical conductor. Otherwise, the object is an insulator. Among the conductors, certain objects will result in a brighter light than others. This will allow students to decide which object is the best electrical conductor.
A spin on the science side
Hands-on experience with gyroscopes is a good way to help children understand rotational motion. Have students experiment with spinning tops on a large, hard, flat surface such as the gymnasium floor. The students should set the tops spinning and make observations about what happens when they push the spinning tops in certain directions. They can try applying force to the gyroscopes at different heights from the ground to see how this affects the movement of a spinning top. All this can be related to gyroscopic principles (such as precession and gyroscopic inertia), as well as applications of these principles (satellites, bicycles, etc.) in real life. If you are unfamiliar with rotational motion, the museum's background information on gyroscopes may be of some assistance.
To learn more about rotating bodies, present this question: Which will spin longer, a hard-boiled egg or a raw one? Why? Following the scientific method, students can use what they know about gyroscopes to make an educated guess at the answer. They can then test their hypothesis and try to explain their results. It might be a good idea to help students through this process to ensure that they understand the concepts of gyroscopes and don’t end up believing in false assumptions.
If your class is old enough, ask the students to find out how various appliances in their homes work. A different appliance (fridge, stove, toaster, vacuum cleaner etc.) could be assigned to each student or small group of students. Suggest that students try to find information outside the library: Look on the Internet, telephone the appliance dealer or repair service, or ask a parent or friend who would know about the appliance through his or her job. The students could then present their findings to the class.
Ask students to make a list of things in their homes that use electricity. Then, as a class or in smaller groups, discuss how people in other countries live differently, with different appliances or without any appliances at all. Perhaps some background information could be researched by the teacher or by older students to find out about different cultural practices and lifestyles. A valuable resource might even be class members of different national heritage who can ask their parents about their home countries, or who have first-hand experience of living in a different culture themselves. Areas of lifestyles to compare could include transportation, cooking, housing construction and repair or leisure-time activities. It might be especially interesting to compare how needs are met -- by electricity or by other means -- in countries of completely different climates.
This activity is appropriate for students who have already learnt about cryogenics, through the museum's school program demonstration or through other means. Information about this subject can be found at: cryogenics background.
Ask the students to write a story about an imaginary world where everything is very cold. They should try to remember how objects in the demonstration reacted to liquid nitrogen, and apply this to objects and events involved in their story. For example, rubber would be hard, and human exposure to the cold would be very dangerous. Alternatively, the story could take place at home, but on an unusually cold day. This type of story could begin: "I walked out the door on my way to school one very cold day last winter. It was so cold that...."
Exploring the world with the scientific method
Hold a class discussion about the scientific method (described at the beginning of the Math, Science and Technology section). Ask students to think of its advantages and disadvantages. Students can talk about how the scientific method can lead to consistent and comprehensive results. They could try to think about how scientists use the scientific method to conduct their experiments and to communicate their ideas and findings with each other and with the public.
Ask the students to invent, design and draw a machine of the future to perform a task that would make everyday life a little easier. The machines could be useful in the home, for transportation or for manufacturing, for example. When designing their machines, the students should make use of cold temperatures, chemical reactions (such as those seen in the school program), gyroscopic inertia or precession, and/or static electricity. Click on the underlined terms or go to the background information section to learn more about these subjects. This activity should encourage creativity. Challenge students to invent the craziest machine they can think of.
A spin on the science side
This lesson plan idea is based on an activity from the Newton's Apple web site located at http://ericir.syr.edu/Projects/Newton/. This site is a good source of scientific information and ideas for experiments.
After the gyroscopes demonstration, the students can build and decorate their own gyroscopes out of a 40-cm length of string, a matchstick or toothpick, and an old LP record. Begin by having the students decorate their records; they could paint them or glue coloured paper to their surfaces. Tie a knot around the centre of the matchstick with one end of the string. Thread the free end of the string through the hole in the record, so that the record is suspended flat on the matchstick when you hold the free end of the string. Grasping the free end of the string, push the record so that it swings back and forth like a pendulum. Now spin the record and then try to swing it again. What happens? "Gyroscopic inertia is the property of a rotating object to resist any external force which would change its axis of rotation. Once the record is set spinning at an angle perpendicular to the string, it will resist any forces (such as gravity) that try to change that angle." - Newton’s Apple
Science and Technology 
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