Torpedo Designing Contest
Summary
In this combined Chemistry and Physics lab, students will investigate how to create the best two pipette torpedo that will be propelled using the chemical reaction of baking soda and vinegar. Students first have to design a success shape of a torpedo and then, using knowledge gained about limiting reagents, determine the correct amount of baking soda and vinegar. The investigation is a transitional stage between chemistry and physics. The physics portion of the investigation involves the students calculating distance, time and velocity of their torpedoes.
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Learning Goals
The goals of the investigation is for student to use critical thinking skills to come up with the best torpedo design, data analysis of the classrooms velocity averages and transfer of previous knowledge used in chemistry and physics into a real world application. Students will learn other skills that include drafting, designing, team work, and fluid dynamics. By the end of the investigation students should master the concept of velocity computation and the determination of limiting reactant. Student will have to use words like excess reactant, limiting reactant, velocity, distance and time to successfully complete the investigation.
Context for Use
This investigation is incorporated into a regular or honors chemistry classroom of 16-18 year. The investigation will take approximately one week of classroom time. The time could be adjusted in the classrooms if they are smaller than 25. The investigation could use some of the following materials depending on if the students think about using that equipment: 12 foot section of a capped rain gutter filled with water for torpedo launching, 15 ml plastic pipettes, razors, scissors, tape of various kinds, hot glue gun, news paper, baking soda, vinegar and electronic balances. Prior to this lesson students have been instructed on how to use balances, measure chemicals properly and calculations on chemical reactions needs i.e. moles, molecules and limiting reactants via stoichiometry. This is the culminating activity in the curriculum for limiting reactants and it is partly a transition into the physics curriculum. It would be easy to adapt to a physics classroom but sometimes the physics classrooms do not have the water drain in the classroom. The investigation can be adapted for younger levels if the students work entirely on the design of the torpedo and not the chemical nature of the propulsion.
Description and Teaching Materials
The investigation is introduced at the end of the limiting and excess reactants unit in the chemistry curriculum. The students are given the attached investigation guide along with two torpedoes. The students are told that during this week of class they need to design, create and test a torpedo for the class competition on the 5th day of the investigation. Students are then led through the handout to point out the major parts of the investigation. It is pointed out that the procedure is not a guess and check approach but rather they are to make serious calculations of the amounts of materials they need. The students are given the two pipettes. No other materials besides balances and water will be provided. The students need to supply all of their own glue, tape, scissors and anything that they might use.
During the design processes, students should come up with the shape of their torpedo first then determine the limiting reactant by filling up the design with each ingredient. Once they know the max amount of baking soda and vinegar they can use, determine which reactant will run out first. If students do this first then they can start measuring, testing and adapting their design.
Students will spend four days working and testing their designs. During this time they should have the teacher record 5 trials to keep tally on how the group is doing. While the students are working on designs the teacher should go around and help those students who are having trouble with their work. Some groups do not have the engineering ability to create a torpedo out of pipettes. Some groups will also need to be given reminders on the mathematics behind the chemical process. This time should also be spent keeping groups away from each other so that design stealing does not happen.
On the final day, each group gets two chances to show the teacher their torpedo designs and then let their torpedo go. The teacher will record the distance and time. This will be used later to determine their grade and class averages. The groups that day will need to go fast and be ready to do their runs.
After the 5th day the averages will be taken of the class data and given back to the students. They are to use this data to compare their results to the whole. The students are then given one full week to complete the investigation write up.
During the design processes, students should come up with the shape of their torpedo first then determine the limiting reactant by filling up the design with each ingredient. Once they know the max amount of baking soda and vinegar they can use, determine which reactant will run out first. If students do this first then they can start measuring, testing and adapting their design.
Students will spend four days working and testing their designs. During this time they should have the teacher record 5 trials to keep tally on how the group is doing. While the students are working on designs the teacher should go around and help those students who are having trouble with their work. Some groups do not have the engineering ability to create a torpedo out of pipettes. Some groups will also need to be given reminders on the mathematics behind the chemical process. This time should also be spent keeping groups away from each other so that design stealing does not happen.
On the final day, each group gets two chances to show the teacher their torpedo designs and then let their torpedo go. The teacher will record the distance and time. This will be used later to determine their grade and class averages. The groups that day will need to go fast and be ready to do their runs.
After the 5th day the averages will be taken of the class data and given back to the students. They are to use this data to compare their results to the whole. The students are then given one full week to complete the investigation write up.
Teaching Notes and Tips
The first part of confusion in this investigation is the design portion. Some students have a difficult time designing objects from different materials than they are used to seeing. The teacher should give a bit of guidance to these students on how torpedoes work. Students will need to be reinforced on the mathematics that are involved in finding the limiting reactants. This is a good idea to write up on the board. Some students will only need a nudge to remember and some will need the entire process taught to them again because they did not master the idea the first time.
During the design process be careful of the hot glue guns, scissors, razors and push pins students might want to or be using. Students usually leave these materials lying around. Be remindful to them that those materials need to be returned up front. As for the chemical safety, students who bring in their own baking soda and vinegar need to leave the materials at school because they now have been contaminated and are no longer food safe.
Some students will fail this investigation because it is hard to "copy" someone else's success. If the student does not work on the torpedo, they automatically get 30% off on their report.
During the design process be careful of the hot glue guns, scissors, razors and push pins students might want to or be using. Students usually leave these materials lying around. Be remindful to them that those materials need to be returned up front. As for the chemical safety, students who bring in their own baking soda and vinegar need to leave the materials at school because they now have been contaminated and are no longer food safe.
Some students will fail this investigation because it is hard to "copy" someone else's success. If the student does not work on the torpedo, they automatically get 30% off on their report.
Assessment
The assessment of students is base on their distance their torpedo travels and the torpedo's velocity. The usual distance for 10 out of 10 points is 1.5-2 meters. Then the grading scale and be applied to that. 1.8 meters out of 2 meters could be a 9 out of 10 points (90%). Velocity is graded on 1 meter per second gets 5 out of 5 points. Some students will label this feet per second or miles per hour, so be careful to correct them. I then curve down to 1 out of 5 points if the torpedo goes forward no matter how slow.
The rest of the grading is done on the student's report they turn in. The report has several parts including introduction, design, calculations, data, results, analysis. The students usually miss points on the calculations portion. The analysis is the best part to see how the student worked through the investigation and to see if they truly realize their successes and failures.
The rest of the grading is done on the student's report they turn in. The report has several parts including introduction, design, calculations, data, results, analysis. The students usually miss points on the calculations portion. The analysis is the best part to see how the student worked through the investigation and to see if they truly realize their successes and failures.
Standards
1.1.2
1.2.1
2.2.1
2.2.2
2.1.2
2.3.2
1.2.1
2.2.1
2.2.2
2.1.2
2.3.2