Academic journal article Science Scope

Using an Everyday Object to Explain Air Pressure

Academic journal article Science Scope

Using an Everyday Object to Explain Air Pressure

Article excerpt

How can the use of a simple straw help students understand the effects of air pressure on their daily lives? As a middle school science teacher with almost 30 years of experience, I have witnessed the positive impact of learning cycles as an inductive approach to concept formation.

Student exploration changes misconceptions, promotes interest, motivates learners, and alters attitudes (Bruner 1960; Dewey 1967; Martin et al. 2005; Piaget 1970; Turkmen and Usta 2007). The Next Generation Science Standards (NGSS) and A Framework for K-12 Science Education, upon which the NGSS is based, agree. No matter how instruction is administered, the result should be that students "generate and interpret evidence and develop explanations of the natural world through sustained investigations" (NRC 2012, p. 255). Additionally, reading lab procedures and writing lab reports are promoted by the Common Core State Standards (NGAC and CCSSO 2010; see Connections to the Standards sidebar).

The activities described in this article allow students to apply their understanding of air pressure to a gadget we use daily.

Groundwork for the Straw Mini--Learning Cycle

Over two centuries ago, scientists Daniel Bernoulli, Jacques Charles, and Robert Boyle investigated how speed, temperature, volume, and air pressure are related. In Appendix H, the NGSS specifically argue for the use of examples from science history in the form of scientist case studies, which help develop students' understanding of how science works. To help my students view science as a human endeavor, I constructed biographies of these brilliant people. (Find the biographies and a list of references used to compose them at www. nsta.org/middleschool/connections.aspx.)

To help my seventh graders build an understanding of the discoveries of Bernoulli, Charles, and Boyle, I created a unit on the laws of fluids that consists of four mini--learning cycles. Students' objective is to discover conditions that affect air pressure. Examples of group activities from Cycles 1, 2, and 3 are as follows;

* To observe Bernoulli's principle, which states that an increase in the speed of a gas or liquid causes a decrease in pressure, students arrange two books 4 cm apart, place a sheet of paper over the gap between the books, blow air through the opening, and watch the paper dip into the gap.

* To examine Boyle's law, which explains the relationship between pressure and the volume of a gas, students pour water into a funnel attached to a clay-sealed bottle and an unsealed bottle, then note that the water remains in the funnel of the sealed bottle.

* The teacher inserts a deflated balloon into an Erlenmeyer flask, stretches the neck of the balloon over the opening of the flask, and places the flask into beakers of hot and cold water. To observe Charles's law, which states that the volume of a gas increases as the temperature increases, students inspect the balloon expanding and contracting.

The Straw Mini--Learning Cycle

The exploration phase

After students complete the cycles above, the groundwork has been laid to close the unit by carrying out the Straw Mini--Learning Cycle. My seventh graders apply their newly constructed knowledge by investigating something they have all experienced: drinking through a straw. Their objective is to explain how a straw really works. After demonstrating the procedures for the Straw Mini--Learning Cycle: Part 1, Part 2, and Part 3 (see Figure 1), I turn the exploration over to my students and become the facilitator. For health reasons, all students are given their own plastic cup and clear straw. Chemical splash goggles should be worn. Students fill their plastic cups about halfway with water. As groups of four students sit at their tables, I add food coloring to make it easier to observe the water level. In the Straw: Part 1, students do what they have all done while waiting to be served in a restaurant: They place their straw in the cup of water, put their finger over the opening at the top of the straw, and remove the straw from the cup. …

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