​​​​​​​​​​The use of dynamic audio-visual aids in the classroom has become widely accepted.  Personal computers connected to small video projectors are now commonly used in K-12 science classrooms to present videos and oral presentations.  Brief descriptions of some of the presentations that TOPS volunteers and their teacher partners use appear on this page.  These A-V presentations are available to volunteers and web site guests in Microsoft PowerPoint® file format. Click on the blue button for the specific presentation you would like to save. You can then rename, save and view or print the file.

The Structure of Simple Carbohydrates

This lesson describes the nature carbohydrates and teaches students the difference between molecular formulas and structural formulas.  

Glue Ball Chemistry

The nature and structure of polymers are discussed in this presentation. In addition, the students are instructed to perform a simple experiment that enables them to convert a small amount of Elmer’s glue to a rubber ball using the concept of polymer “cross-linking.”  

Physical and Chemical Changes

The differences between physical and chemical changes as well as the clues to a chemical reaction are described in this presentation.  It is used as a prelude to the demonstration of “Halloween Colors,” the reaction between hydrogen peroxide and potassium dichromate, which involves multiple chemical reactions occurring at different rates.

Laws of Conservation of Mass and Definite Proportions

The two laws are defined and the reaction between sodium bicarbonate and acetic acid is analyzed in detail.  The presentation is used prior to a demonstration with a rigid bottle containing the reactants on a triple beam balance. The calculations are shown to prove that the mass of the products of a chemical reaction are equal to the mass of the reactants, and that the law of definite proportions is followed.   

The Difference between Mass and Weight 

This short lesson explains the difference between mass and weight and the connection between them.

The Measurement of pH

The definition of pH, how the scale is made, and the techniques used to measure it are described.   This presentation is intended to be used in conjunction with the activity where students prepare  dilute solutions of orange juice and measure their pH.  


Origin of the Elements

Theories of how the universe was formed and the origin of the elements are described. Starting with hydrogen, the lesson shows how the elements were created by nuclear fusion in stars, novas, and supernovas.


Oscillating Chemical Reaction

This presentation includes a video that shows the Briggs-Rauscher reaction, a rare example of an oscillating chemical reaction that produces alternating changes in color over many cycles.  The discoverers of the reaction are high school teachers, so the chemistry described in the presentation is aimed at advanced Middle School students.


Self Darkening Sunglasses

An example of a reversible chemical reaction used in glasses that darken in sunlight and become clear in ordinary room is briefly described.  The concept is known as “photochromism” and the presentation shows how the molecule’s structure changes from one form to another in light and dark.

The Scientific Method

Intended for presentation early in the first semester of Middle School physical science, this talk covers the definition of science, discusses how scientists work, and outlines the steps involved in the scientific method. There is also a discussion of measurements and the importance of science in today's world.

Another presentation uses the example of the discovery and development of liquid crystal displays to show how the scientific method was applied.


The Decomposition of Sugar (Sucrose)

A short video shows a demonstration of the acid-catalyzed decomposition of common table sugar (sucrose).  The mechanism of the dehydration reaction that occurs is shown by the use of structural formulas.  The video can be viewed on this website at the Instructional Video page.  A PowerPoint presentation with the same content is also available.

The Meaning and Use of Pi

A short presentation of how the constant pi was derived and how it is used.


Liquid Crystals: A Unique State of Matter

Although not part of the required curriculum, this PowerPoint presentation is given to teach students about liquid crystals and how they are used in today's ubiquitous flat panel displays for computers and television as well as cell phones and other hand-held devices.

Rocket Science Fundamentals

Some middle schools have elective courses in aeronautics and rocket science/engineering.  This fourteen minute slide show is an introduction to rocketry and the structure of the Minuteman III Intercontinental Ballistic Missile as well as some future propulsion system designs. 

The Electrolysis of Water

One of the best demonstrations of the decomposition of water into hydrogen and oxygen uses the Hofmann Apparatus to measure and collect the gases.

A demonstration of water electrolysis that uses a simple set-up is shown in a short video that can be viewed on the Instructional Video page on this website.  The gases cannot be measured or collected, but students can see many more bubbles of hydrogen than oxygen being released from the electrodes.  A PowerPoint presentation is also available by clicking on the following button.

Organic Chemistry Basics

This ten minute PowerPoint slide show presentation provides a discussion of the basics of organic chemistry that are part of the California middle school standards.  It covers covalent bonding, structural formulas, functional groups, polymers, amino acids and proteins.  

Compounds of Life
This discussion of the biological molecules present in living organisms is intended to follow the presentation on Organic Chemistry Basics.  The six minute PowerPoint slide presentation covers material contained in California middle school school standards.  It covers the basics of amino acids, proteins, nucleic acids, lipids and carbohydrates.

Polymers & Composites

The fundamentals of polymer chemistry and their use in composites are described in this presentation.   A brief history of the development of the various types of and classes of commonly used polymers  is also given.

Nylon Fiber Formation

This slide show presentation discusses the synthesis of nylon and includes a video that shows the formation of nylon fiber

Acknowledgement:  Many thanks to Mrs. Hope Oliver, Science Department Head, Bret Harte Middle School, San Jose, California, for help in developing many of the above presentations.


TOPS of Santa Clara Valley

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