All biological cells require the transport of materials across the plasma membrane into and out of the cell. By infusing cubes of agar with a pH indicator, and then soaking the treated cubes in vinegar, you can model how diffusion occurs in cells. Then, by observing cubes of different sizes, you can discover why larger cells might need extra help to transport materials.
High School Chemistry
This set of a teacher and student guides provides instruction on a 2-3 day series of activities about Le Chateliers principle, which shows the effect of changes to conditions in an equilibrium reaction. Students work in pairs or groups to develop their concepts of equilibrium and the effects of changing the amount of reactants or products on an equilibrium system. The concepts are presented and analyzed using graphical representations, qualitative lab data, and modelling. The first part addresses the misconception that equal amounts are required for equilibrium through using a mini-activity that involves the transfer of water between beakers. The second part is a lab activity where students will see how an equilibrium system reacts to a change in concentration. The third part uses manipulatives to understand how an equilibrium operates using the mathematical equilibrium constant (Ksp) at the particulate view.
The purpose of this video lesson is to expand the student's knowledge about enzymes by introducing the antioxidant enzymes that are intimately involved in the prevention of cellular damage and eventual slowing of the aging process and prevention of several diseases. Students will learn that natural antioxidant enzymes are manufactured in the body and provide an important defense against free radicals. The topic of free radical action is introduced, covering how they are constantly generated in living cells both by ''accidents of chemistry'' and also by specific metabolic processes.
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.
Students learn about various crystals, such as kidney stones, within the human body. They also learn about how crystals grow and ways to inhibit their growth. They also learn how researchers such as chemical engineers design drugs with the intent to inhibit crystal growth for medical treatment purposes and the factors they face when attempting to implement their designs. A day before presenting this lesson to students, conduct the associated activity, Rock Candy Your Body.
Students act as engineers to learn about the strengths of various epoxy-amine mixtures and observe the unique characteristics of different mixtures of epoxies and hardeners. Student groups make and optimize thermosets by combining two chemicals in exacting ratios to fabricate the strongest and/or most flexible thermoset possible.
Student groups construct simple conductivity probes and then integrate them into two different circuits to test the probe behavior in solutions of varying conductivity (salt water, sugar water, distilled water, tap water). The activity culminates with student-designed experiments that utilize the constructed probes. The focus is to introduce students to the fabrication of the probe and expose them to two different ways to integrate the probe to obtain qualitative and quantitative measurements, while considering the application and utility of a conductivity probe within an engineering context. A provided handout guides teams through the process: background reading and questions; probe fabrication including soldering; probe testing and data gathering (including circuit creation on breadboard); probe connection to Arduino (including circuit creation and code entry) and a second round of testing and data gathering; design and conduct their own lab experiments that use the probes; online electrolyte/nonelectrolyte reading, short video, comprehension check and analysis questions.
In this demonstration, cook a cake using the heat produced when the cake batter conducts an electric current. Because of safety concerns, this activity should be conducted as a demonstration only and learners should be kept at a safe distance.
This video lesson aims to motivate students about chemistry and to raise their awareness about how chemistry helps in solving certain environmental problems. In this lesson, the air pollution problem created by cars and other vehicles is presented. The lesson will highlight causes of this problem, harmful products from it and possible solutions. There will also be discussion of ways to convert the pollutants produced by burning oil in vehicles into more friendly products.
Polymers are a vital part of our everyday lives and nearly all consumer products have a plastic component of some variation. Students explore the basic characteristics of polymers through the introduction of two polymer categories: thermoplastics and thermosets. During teacher demos, students observe the unique behaviors of thermoplastics. The fundamentals of thermoset polymers are discussed, preparing them to conduct the associated activity in which they create their own thermoset materials and mechanically test them. At the conclusion of this lesson-activity pair, students understand the basics of thermoplastics and thermosets, which may entice their interest in polymer engineering.
Students investigate the property dependence between concentrations and boiling point. In section 1, students first investigate the boiling point of various liquid solutions. In section 2, they analyze data collected by the entire class to generate two boiling point curves, one for salt solutions and one for sugar solutions. Finally, in section 3, students use the data they have analyzed to determine how to create a solution that has a particular boiling point and is a cost-effective design.
In this activity, learners conduct an oxidation experiment that turns old pennies bright and shiny. Learners soak 20 dull, dirty pennies in a bowl of salt and vinegar for five minutes. They rinse half the pennies with water, then compare the rinsed pennies to the unrinsed after all pennies sit and dry for about an hour. Learners also observe what happens when they submerge a screw and nail in the liquid compared to a nail only half-way submerged.
This 11-minute video lesson works through a calculation for K-Ar dating (it is good to have some prior experience with e and logarithms to understand). [Cosmology and Astronomy playlist: Lesson 80 of 85]
This 11-minute video lesson looks at Potassium-Argon (K-Ar) dating and it can be used to date very old volcanic rock and the things that might be buried in between. [Cosmology and Astronomy playlist: Lesson 79 of 85]
Concluding a two-part lab activity, students use triple balance beams and graduated cylinders to take measurements and calculate densities of several household liquids and compare them to the densities of irregularly shaped objects (as determined in Part 1). Then they create density columns with the three liquids and four solid items to test their calculations and predictions of the different densities. Once their density columns are complete, students determine the effect of adding detergent to the columns. After this activity, present the associated Density & Miscibility lesson for a discussion about why the column layers do not mix.
After students conduct the two associated activities, Density Column Lab - Parts 1 and 2, present this lesson to provide them with an understanding of why the density column's oil, water and syrup layers do not mix and how the concepts of density and miscibility relate to water chemistry and remediation. Topics covered include miscibility, immiscibility, hydrogen bonds, hydrophobic and hydrophilic. Through the density column lab activities, students see liquids and solids of different densities interact without an understanding of why the resulting layers do not mix. This lesson gives students insight on some of the most fundamental chemical properties of water and how it interacts with different molecules.
Students demonstrate the erythrocyte sedimentation rate test (ESR test) using a blood model composed of tomato juice, petroleum jelly and olive oil. They simulate different disease conditions, including rheumatoid arthritis, anemia, leukocytosis and sickle-cell anemia, by making appropriate variations in the particle as well as in the fluid matrix. Students measure the ESR for each sample blood model, correlate the ESR values with disease conditions and confirm that diseases alter blood composition and properties. During the activity, students learn that when non-coagulated blood is let to stand in a tube, the red blood cells separate and fall to the bottom of the tube, resulting in a sediment and a clear liquid called serum. The height in millimeters of the clear liquid on top of the sediment in a time period of one hour is taken as the sedimentation rate. If a disease is present, this ESR value deviates from the normal, disease-free value. Different diseases cause different ESR values because blood composition and properties, such as density and viscosity, are altered differently by different diseases. Thus, the ESR test serves as a real-world diagnostic screening test to identify indications of the presence of any diseases in people.