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.

Biology 2e is designed to cover the scope and sequence requirements of a typical two-semester biology course for science majors. The text provides comprehensive coverage of foundational research and core biology concepts through an evolutionary lens. Biology includes rich features that engage students in scientific inquiry, highlight careers in the biological sciences, and offer everyday applications. The book also includes various types of practice and homework questions that help students understand—and apply—key concepts. The 2nd edition has been revised to incorporate clearer, more current, and more dynamic explanations, while maintaining the same organization as the first edition. Art and illustrations have been substantially improved, and the textbook features additional assessments and related resources.

By the end of this section, you will be able to do the following:

Describe the basic ecosystem types
Explain the methods that ecologists use to study ecosystem structure and dynamics
Identify the different methods of ecosystem modeling
Differentiate between food chains and food webs and recognize the importance of each

By the end of this section, you will be able to do the following:

Define matter and elements
Describe the interrelationship between protons, neutrons, and electrons
Compare the ways in which electrons can be donated or shared between atoms
Explain the ways in which naturally occurring elements combine to create molecules, cells, tissues, organ systems, and organisms

Introduction to ecosystems and other ecological concepts.

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Introduces Hardy-Weinberg equilibrium.

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In this video, Paul Andersen explains how ecosystems respond to disruptions. Disruptions can cause changes in the number and variety of organisms. It can also lead to migration, extinction or even speciation. Ecosystems that have higher biodiversity are able to respond to large disruptions over time. [6:52]

Paul Andersen explains how acid-base chemistry can be understood in terms of equilibrium. Water is present in all acid-base chemistry and is amphoteric in nature. The Ka and Kb values can be used to determine the strength of an acid or a base. Titrations can be used to student neutralization reactions between strong and weak acids and bases. [10:27]

We can combine our knowledge of acids and bases, equilibrium, and neutralization reactions to understand buffers and titrations. Solubility equilibria will build on concepts from solubility, precipitation, and equilibrium.

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

Acting as an overview from the General Chemistry Virtual Textbook, this site explores a range of topics related to chemical equilibrium including chemical change, the LeChatelier principle, the equilibrium quotient, and more.

Acting as an overview from the General Chemistry Virtual Textbook, this site provides an overview of information related to Le Chatelier's Principle. Various topics covered include the le Chatelier Principle and physiology, how changes in temperature affect equilibria, how changes in pressure affect equilibria, and more.

This Chem4Kids.com site explains what equilibrium is in easy-to-understand language. Content includes a great example, as well as exploring different things which effect the position of equilibrium.

This site provides a detailed overview of chemical reactions. Content explores what a reaction is, as well as different types of reactions, reaction rates, how to measure compounds to create a reaction, and "stuff" you can add to a reaction to speed it up or slow it down.

This digital textbook covers core chemistry concepts and includes interactive features, real-world examples, and videos.

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Summarizes the key points about the evolution of agriculture and how it has impacted human population growth. Includes a few questions to check for understanding.

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This game helps students to understand the concepts of changing supply, changing demand, and equilibrium price, as the price of bags of ice changes after a hurricane has swept through a community.