The National Science Education Standards released in 1996 focus the experience of the middle school learner on three core areas: physical, life and earth and space sciences. Students engaged in physical science study three main areas: motion and forces, transfer of energy, and properties and changes in matter. Because science is of an investigative nature, all three of these areas lend themselves to hands-on, inquiry-based projects.
Motion, Forces and Energy: Soda Pop Can Engine
Open a soda can and empty the contents. Use an awl to punch four holes into the base of the can just above the lower rim and 90 degrees apart from each other. When the awl penetrates the can wall, rotate it clockwise to direct the water flow out of the can. Raise the can opener tab and tie a string to it. Hang the can above a sink. Fill the can with water and watch as the release of water causes the can to move in the opposite direction, demonstrating Newton's third law of motion: every action has an equal and opposite reaction.
Potential and Kinetic Energy: Spool Car
Gather up thread spools that no longer have thread on them. Set up small objects as targets to be moved around. The objects can be masses with different weights. Use rubber bands to create a simple sling shot -- using the thumb and pointer finger is fine. Draw the spool back so that it can be fired to roll across a flat surface. The spool should be aimed at the masses so the effect of the impact can be observed. Run several trials for each mass, drawing the rubber band back the same amount each time, and record the observations. Repeat the trials again, using more rubber bands or greater stretching distances. The ability to demonstrate the transfer of energy is shown with rubber bands as the potential energy source. Since the spools are used to displace objects, students get a concrete understanding of the energy transfer. The more energy a rubber band has, by stretching the rubber band further, the more power the spool will have to displace the mass.
Properties of Matter -- Changes of State: Instant Freeze
The change from a liquid state to a solid one is probably the most common change in matter in the ordinary world. Every kid seems to know that water becomes ice. But the process of freezing is one that is hard to watch because it occurs over time. With this demonstration the process comes to life right before the students' eyes. The freezing occurs quickly and at a temperature different from water, so students are forced to search for a deeper understanding of what happens to the liquid and why. Put several plastic soda bottles into the fridge for at least four hours. Set up an ice bath with rock salt to lower the freezing point. Place the soda bottles in the salt bath for at least 10 minutes. Put a thermometer near the bottles to measure the temperature. The temperature needs to get to freezing. Once frozen, open the soda bottle. Be careful as ice will shoot out.
Properites of Matter -- Density: Coke vs. Diet Coke
Get two cans of Coca-Cola -- one regular and one diet. Place the cans of soda in an aquarium filled with water so that students can see that Diet Coke cans float and regular Coke cans sink. Have students propose reasons for this. They will need to investigate the cans to test the size, mass and contents. They can create lists of similarities and differences to try to come to a conclusion. Show students the amount of sugar (39g) and Aspartame (188 mg) so that they can see the differences. Continue questions and ideas to help them understand density. By letting students see that the masses are different but the volume is the same, they can begin to understand density. Show the students other soda products and tell them the mass of the can should let them predict whether it will sink or not. Through this, density can be explained.
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