In nature most elements occur as a mixture of two or more isotopes. Eachisotope of an element has a fixed mass with a natural percent abundance. The mass of theelement needs to reflect the masses of these isotopes in their respective abundances. Giventhe masses and abundances, how is the Average Atomic Mass determined?
In this activity, you will determine the atomic mass of the fictitous element Candium.

Both of these lessons are classroom activities that require students to build models that display understanding of atoms and molecules. One lesson is structured while the other is guided.

This is a laboratory activity in which students will compare the amount of carbon dioxide in four different sources of gas and determine the carbon dioxide contribution from automobiles. They test ambient air, human exhalation, automobile exhaust, and nearly pure carbon dioxide from a vinegar/baking soda mixture.

Students are introduced to the concept of engineering biological organisms and studying their growth to be able to identify periods of fast and slow growth. They learn that bacteria are found everywhere, including on the surfaces of our hands. Student groups study three different conditions under which bacteria are found and compare the growth of the individual bacteria from each source. In addition to monitoring the quantity of bacteria from differ conditions, they record the growth of bacteria over time, which is an excellent tool to study binary fission and the reproduction of unicellular organisms.

Students visualize and interact with concepts already learned, specifically algebraic equations and solving for unknown variables. They construct a balancing seesaw system (LEGO® Balance Scale) made from LEGO MINDSTORMS® parts and digital components to mimic a balancing scale. They are given example algebraic equation problems to analyze, configure onto the balance scale, and evaluate by manipulating LEGO pieces and gram masses that represent terms of an equation such as unknown variables, coefficients and integers. Digital light sensors, built into the LEGO Balance Scale, detect any balance or imbalances displayed on the balancing scale. The LEGO Balance Scale interactively issues a digital indication of balance or imbalance within the system. If unbalanced, students continue using the LEGO Balance Scale until they are confident in their understanding of solving algebraic equations. The goal is for students to become confident in solving algebraic equations by fundamentally understanding the basics of algebra and real-world algebraic applications.

Play with objects on a teeter totter to learn about balance. Test what you've learned by trying the Balance Challenge game.

How do you know if a chemical equation is balanced? What can you change to balance an equation? Play a game to test your ideas!

Students investigate different balls' abilities to bounce and represent the data they collect graphically.

This activity is an extension of the common balloon cars, where students explore if and how different gases used as a fuel source effect the distances traveled by the cars.

Experiment with a helium balloon, a hot air balloon, or a rigid sphere filled with different gases. Discover what makes some balloons float and others sink.

Experiment with a helium balloon, a hot air balloon, or a rigid sphere filled with different gases. Discover what makes some balloons float and others sink.

Why does a balloon stick to your sweater? Rub a balloon on a sweater, then let go of the balloon and it flies over and sticks to the sweater. View the charges in the sweater, balloons, and the wall.

Explore the origin of energy bands in crystals of atoms. The structure of these bands determines how materials conduct electricity.

Explore the origin of energy bands in crystals of atoms. The structure of these bands determines how materials conduct electricity.

Students hypothesize whether vinegar and ammonia-based glass cleaner are acids or bases. They create designs on index cards using these substances as invisible inks. After the index cards have dried, they apply red cabbage juice as an indicator to reveal the designs.

Students learn the basics of acid/base chemistry in a fun, interactive way by studying instances of acid/base chemistry found in popular films such as Harry Potter and the Prisoner of Azkaban and National Treasure. Students learn what acids, bases and indicators are and how they can be used, including invisible ink. They also learn how engineers use acids and bases every day to better our quality of life. Students' interest is piqued by the use of popular culture in the classroom.

This is a free textbook offered by Saylor Foundation. The Basics of General, Organic, and Biological Chemistry by David W. Ball, John W. Hill, and Rhonda J. Scott is a new textbook offering for the one-semester GOB Chemistry course. The authors designed this book from the ground up to meet the needs of a one-semester course. It is 20 chapters in length and approximately 350-400 pages; just the right breadth and depth for instructors to teach and students to grasp. In addition, The Basics of General, Organic, and Biological Chemistry is written not by one chemist, but THREE chemistry professors with specific, complimentary research and teaching areas. David W. Ball’s specialty is physical chemistry, John W. Hill’s is organic chemistry, and finally, Rhonda J. Scott’s background is in enzyme and peptide chemistry. These three authors have the expertise to identify and present only the most important material for students to learn in the GOB Chemistry course.

Look inside a resistor to see how it works. Increase the battery voltage to make more electrons flow though the resistor. Increase the resistance to block the flow of electrons. Watch the current and resistor temperature change.

Look inside a battery to see how it works. Select the battery voltage and little stick figures move charges from one end of the battery to the other. A voltmeter tells you the resulting battery voltage.

Look inside a battery to see how it works. Select the battery voltage and little stick figures move charges from one end of the battery to the other. A voltmeter tells you the resulting battery voltage.