SPEAK OUR LANGUAGE

• CELL – Core Experience Learning Lab
• SDR – Scientist Data Record

ASK WHY

Great scientists question the world around them. We encourage our LabLearner students to do the same. In anticipation of this, we explain the importance of learning the concepts in the Ask Why section within the CELL. Our hope is that these explanations help students understand why science matters.

BRANCH OUT

Each Investigation introduces students to a different branch of science or STEM (Science, Technology, Engineering, Mathematics) career that utilizes the scientific concepts of the CELL. These real-world connections will help students see the relevance of what they are learning. STEM connections are also integrated into each Performance Assessment.

GET FOCUSED

The Focus Questions in each Investigation are designed to help teachers and students focus on the important concepts. By the end of the CELL, students should be able to answer the following questions:

Investigation 1:

• How does the transfer of potential energy to kinetic energy relate to the Law of Conservation of Energy? All of the energy changes observed in the Investigation will be due to the transfer of energy from potential to kinetic or from kinetic to kinetic and not because energy disappeared or was created.

Investigation 2:

• Can one form of energy be converted to another? Support your answer with data from the experiments. In this Investigation, students will observe the conversion of electrical energy to light energy and the conversion of light energy to thermal energy (heat).

• How does converting energy from one form to another relate to the conservation of energy? The Law of Conservation of Energy states that energy cannot be created or destroyed but can be converted from one form to another. Both of the graphs in Investigation Two will show direct relationships for the conversion of electrical energy to light and light energy to heat.

Investigation 3:

• Can one form of energy be converted to another? Support your answer with data from the experiments. Students will observe the conversion of chemical potential energy to kinetic energy.

• How does converting energy from one form to another relate to the Law of Conservation of Energy? The Law of Conservation of Energy states that energy cannot be created or destroyed but can be converted from one form to another. Students will observe a direct relationship between amount of vinegar (chemical potential energy) and the circumference of the balloon.

Note: These are succinct responses to the Focus Questions and are placed here for easy reference. Fully developed responses to the Focus Questions can be found on each PostLab page.

Note: Some questions may be revisited as the CELL progresses. As students acquire additional knowledge, their responses should reflect this.

LEARN THE LabLearner LINGO

The following list includes Key Terms that are introduced within the Backgrounds of the CELL. These terms should be used, as appropriate, by teachers and students during everyday classroom discourse.

Note: Additional words may be bolded within the Background(s). These words are not Key Terms and are strictly emphasized for exposure at this time.

Investigation 1:

• Law of Conservation of Energy: a principle that states that energy is neither created nor destroyed, it simply changes form
• Kinetic Energy: the energy of motion
• Potential Energy: The energy stored in an object or substance.
• Gravitational Potential Energy: the potential energy that exists between two objects that exert a gravitational pull on each other

Investigation 2:

• Electrical Potential Energy: the potential energy that exists when comparing a region of high electrical charge to one of low electrical charge

Investigation 3:

• Chemical Potential Energy: the potential energy stored in the chemical bonds of chemical compounds

BE PREPARED

An overview of the materials for each lab is placed here for easy reference. Specific teacher preparation for the labs is placed at the beginning of each Lab page.

EXTEND YOUR THINKING

The following information is included so that teachers have additional background knowledge pertaining to the concepts introduced in the  CELL. Teachers may choose to use this information to enrich students during instruction by integrating it into individual Concept presentations.

Energy can be categorized into two general types of energy. Potential energy is energy that is not being used, so is often referred to as stored energy. A pencil resting on the edge of a table possesses gravitational potential energy due to its position because it rests at a position somewhere above the center of the Earth. It has the potential of moving toward the center of the Earth if it is pushed off the table. A battery possesses electrical potential energy because its energy is stored between regions possessing high numbers of electrons and regions possessing low numbers of electrons. A gallon of gasoline possesses chemical potential energy in the form of the energy of the chemical bonds of the gasoline molecules. When the pencil falls to the floor, the battery is connected to a circuit, or the gasoline is ignited, potential energy is converted into kinetic energy.

Kinetic energy is the energy of matter in motion. In the examples above, matter is considered to be the molecules of the pencil, the electrons stored in the battery, and the molecules making up the gasoline. When the pencil falls off the table, its potential energy is transformed into kinetic energy as it moves closer to the floor. When the battery is connected to a circuit, the electrons from the negative terminal form an electric current that moves through the circuit toward the positive terminal. The potential energy of the battery is converted into kinetic energy in the form of the current flowing along the wires. When the gasoline is ignited, the potential energy of the chemical bonds of the gasoline is converted into kinetic energy as the gases produced by the explosion move outward as they expand.

The Law of Conservation of Energy states that energy can neither be created nor destroyed. It is simply converted from one form to another. Each of the previous examples illustrates the Law of Conservation of Energy since each type of potential energy can be converted into kinetic energy. The total energy of an object is the sum of its potential and kinetic energies according to the following equation:

The conversion from potential energy to kinetic energy is not an “all-or-none” event. When the pencil is sitting on the edge of the table, 100% of its energy is potential energy. At the moment the pencil impacts the floor, 100% of its energy is kinetic energy. Between the table and the floor, the total energy the pencil is a constant that is the sum of ever changing amounts of its potential and kinetic energies. As the pencil falls and approaches the floor, its potential energy constantly decreases while its kinetic energy constantly increases as its velocity increases. For example, if the pencil has traveled one-third of the distance between the table top and the floor, 67% of the energy is in the form of potential energy, and 33% of the energy is in the form of kinetic energy.

Energy is often referred to as being “lost”, implying that it is destroyed. However, this idea contradicts the Law of Conservation of Energy. In reality, while energy may no longer be useful in a particular system, it cannot be destroyed but is instead converted to another form or transferred to another object. The impact of the pencil with the floor transfers the kinetic energy of the moving pencil to the floor. The matter of the floor undergoes a slight movement unnoticed by an observer since it is so slight. This movement represents an increase of the kinetic energy of the matter of the floor as a result of the transfer of the kinetic energy of the pencil.

Gravitational potential energy exists as the gravitational attraction between two bodies that are separated from one another. It is most often thought of in the context of two planetary bodies, such as the Earth and Moon, which each exert gravitational forces on one another. The falling pencil is also an example of the effect of gravitational potential energy since each body exerts a gravitational force on the other. The force of the Earth’s gravity on the pencil is obvious since the pencil falls toward the Earth. What is not obvious is that the pencil exerts a gravitational force on the Earth since it is infinitesimal in size.

In Investigation 2, students will investigate electrical potential energy which can be converted into the kinetic energy of moving electrons. Electrons possess a negative charge making them attractive to matter with a positive charge. This attraction can be thought of as electrical potential energy if the electrons are separated from the positive charge by an incomplete circuit. The flow of electrons toward a positive charge results in the movement of electrons with a certain kinetic energy. An electrical current or electricity represents the flow of electrons along a path that consists of a metal wire or other conductor.

The kinetic energy resulting from the movement of electrons can be converted into light energy. As the moving electrons impact the filament in an incandescent light bulb, the kinetic energy of the electrons is transferred to the atoms of the filament which is usually made of tungsten. The kinetic energy of the atoms increases causing the temperature of the filament to increase. The heat increases the kinetic energy of the electrons of the tungsten atoms which release this kinetic energy as photons of light.

In Investigation 3, students will explore how changing the amount of a chemical reactant changes the amount of chemical potential energy in a reaction. A chemical reaction occurs when two or more chemical compound or reactants interact to form new chemical compounds called a product(s). In a chemical compound, the chemical potential energy is stored in the chemical bonds between the atoms that constitute the compound. When a chemical reaction occurs, the chemical bonds of the reactants are broken and new chemical bonds are formed.

In some reactions, the reactants contain a greater amount of chemical potential energy than the products resulting from the reaction. This excess chemical potential energy is released from the reaction. The released energy is often converted to heat and light energy as occurs when gasoline is ignited. The released energy can also be converted into kinetic energy, especially if a product of the reaction is an expanding gas. In the case of gasoline, products of its ignition are carbon dioxide gas and water vapor. The reaction results in a conversion of some of the chemical potential energy to the kinetic energy as these gases expand outward.

In summary, students will begin this CELL by experimenting with kinetic energy, the energy of motion, and observing the effects of velocity on kinetic energy. Potential energy will be introduced, along with the equation for gravitational potential energy. Students will examine the effect of height on potential energy and observe the conversion of potential energy to kinetic energy.

The conversion of potential energy to kinetic energy will be further examined by looking at the conversion of electrical potential energy to kinetic energy in the form of light. Students will also observe the transfer of energy from one form of kinetic energy (light) to another form of kinetic energy (thermal energy or heat). Finally, students will explore chemical potential energy and its conversion into kinetic energy.