Lights, Camera, Action! A Filmed Chemistry Demonstration.

National Science Education Standard H.B.3.c: "A large number of important reactions involve the transfer of either electrons (oxidation/reduction reactions) or hydrogen ions (acid/base reactions) between reacting ions, molecules, or atoms. In other reactions, chemical bonds are broken by heat or light to form very reactive radicals with electrons ready to form new bonds. Radical reactions control many processes such as the presence of ozone and greenhouse gases in the atmosphere, burning and processing of fossil fuels, the formation of polymers, and explosions.

Objectives:
-Students will be able to classify a reaction by the 5 basic types.
-Students will be able to predict the products of a chemical reaction.
-Students will be able to balance a chemical reaction.
-Students will be able to calculate the mass of a product formed given the mass of reactants.
-Students will be able to perform safe lab practices.
-Students will be able to calculate the percent yield of a reaction.

Background knowledge:
For successful implementation, students should have a strong background in chemical reaction basics, including classifying the type of reaction, predicting products, balancing, and basic stoichiometry (including percent yield).

Pre-lab slip (completed as homework the night before, student arrive to class with it completed): “10 grams of hydrogen gas is exploded in excess oxygen gas.
1) Identify the type of reaction.
2) Predict the product(s) of this reaction.
3) Balance this reaction.
4) Calculate the mass of each product formed.
5) Which safe lab practices would be necessary for carrying out this reaction?
6) Imagine that you’ve completed this reaction and 4.5 grams of product is created, what is the percent yield?”

Lesson: The instructor divides students into groups of 2 or 3 (based on equipment available). Each group is provided a FLIP camera with tripod, a white board, a dry erase marker, and reactants/supplies for their reaction. Every effort should be made to provide each group with a different reaction. Single/Double replacement reactions are the easiest to complete within the 90 minute period. Examples of appropriate reactions include:
-Decomposition of sodium bicarbonate.
-Baking soda and vinegar (students measure volume of CO2 using an inverted graduated cylinder.
-Magnesium ribbon oxidation.
-Lead nitrate + potassium iodide.
-Aluminum foil + copper sulfate
-Silver nitrate + potassium chromate

Once students are divided into groups, they have the remainder of class to write, film, and edit their chemical reaction demonstration. It’s estimated that of the 80 minutes, students will take 10 minutes to complete the pre-lab process for their given reaction, 20 minutes to intro this discussion on film, 20 minutes to perform the reaction, 20 minutes to film a conclusion, and 10 minutes to clean up. Videos are uploaded to a computer, and 45 minutes of the subsequent class period are utilized to edit the film. Film editing can be completed quickly with the included FLIP cam software. Videos are uploaded to TeacherTube for the school community and as exemplars for the following year.

Grading: Students are assessed on a 3-point scale for their ability to complete each of the following: translate the reaction to chemical formulas, identify the reaction type, predict the reaction products, balance the reaction, calculate the theoretical yield, measure the actual yield, calculate the percent yield, discuss sources of error, speaking with clarity, script originality, and implementation of safe lab practices.

A score of 0 points on the rubric for each line item represents no effort or plan of the topic. A score of 3 points on the rubric represents an error free discussion/implementation of the line item.

Classroom Management: I use a technique developed by one of my former students to ensure that audio quality is good on the videos. When a group is ready to film, one member of the group will say “Quiet on the set!” and hold up an orange placard. This represents to other students that they should whisper.