Investigating Buoyancy, Density, and Fluid Principles: Making a Mini-Submarine
Summary
In this physical science lab, students attempt to make a mini-submarine out of a modified 35mm film canister that needs to sink to the bottom, stay down for at least 10 seconds, and rise back up to the surface. Students design their own experiment with effervescent tablets, pennies, and their materials, identifying independent and dependent variables and procedure. When they have the right conditions, students are required to perform an official trial in front of their teacher. As a follow-up, students explain how the submarine sinks and floats, using vocabulary and principles being discussed in class such as density, buoyancy, and Archimedes' Principle.
CollapseLearning Goals
This activity is designed for students to:
1. use scientific methods to design an experiment.
2. write a procedure that creates reproducible results.
3. apply appropriate science concepts to observations made in lab.
Key Concepts:
1. Buoyant forces from a fluid allow objects to float in it.
2. Archimedes' Principle relates the weight of the object to the buoyant force of the fluid (in this case, water).
3. Density of an object changes when a gas replaces water in the film canister.
Vocabulary Words:
Buoyancy and Archimedes' Principle
Density
Pressure and Pascal's Principle
1. use scientific methods to design an experiment.
2. write a procedure that creates reproducible results.
3. apply appropriate science concepts to observations made in lab.
Key Concepts:
1. Buoyant forces from a fluid allow objects to float in it.
2. Archimedes' Principle relates the weight of the object to the buoyant force of the fluid (in this case, water).
3. Density of an object changes when a gas replaces water in the film canister.
Vocabulary Words:
Buoyancy and Archimedes' Principle
Density
Pressure and Pascal's Principle
Context for Use
This lab is used with 9th graders in Physical Science working in groups of 2-3. They are given the problem the day before the lab and come in with their hypothesis and overall experimental design. They are given 40 minutes to experiment and show the official trial. Most groups are successful with the official trial, although a few groups are successful during experimenting and cannot reproduce the result for the official trial.
Description and Teaching Materials
This lab is done after discussing differences between solids, liquids, and gases; gas laws; Bernoulli's, Archimedes', and Pascal's Principles; and discussing applications in class. This lab is intended as a review and assessment.
Materials allotted to each lab group
- Film canister with a hole in the lid
- Bottom half of a plastic bottle (20 oz. bottles or 2 L bottles work well)
- Pennies, washers, or other weights
- One effervescent antacid tablet (includes experiment AND official trials)
- Tap Water
Students attempt to explain how/why the submarine floats and sinks using appropriate principles. Before turning the sheet in, the whole class discusses the responses. current assignment handout (Microsoft Word 43kB Sep18 08)
Materials allotted to each lab group
- Film canister with a hole in the lid
- Bottom half of a plastic bottle (20 oz. bottles or 2 L bottles work well)
- Pennies, washers, or other weights
- One effervescent antacid tablet (includes experiment AND official trials)
- Tap Water
Students attempt to explain how/why the submarine floats and sinks using appropriate principles. Before turning the sheet in, the whole class discusses the responses. current assignment handout (Microsoft Word 43kB Sep18 08)
Teaching Notes and Tips
This lab has been used as a review for several years. It started out as a simple execution lab-accomplish the task, fill in the sheet, and turn it in. Now I'll be using it more as heavy reinforcement of experimental design, where students have to carefully think about the variables and procedures.
Adaptations:
- Have groups experiment and write the procedure for the successful submarine. The following day, a different group will use the written procedure to execute the submarine. This will reinforce having clear written procedures and the idea that lab results should be repeatable.
- To keep all students working throughout the period, have students experiment and save materials for the official trial. Ten minutes before class ends, run an official trial for all groups all at once to see who is successful so everyone can watch the different methods.
Tips
1. Lab Safety: I do have students wear goggles.
2. Students worry about not having enough effervescent tablets, so they'll have to carefully plan how they will use it.
3. Students do not get their tablet until they show a brainstorm plan. They lose experiment time if they need to create their brainstorm while others begin their lab.
4. There hasn't been a "correct" way to do this. The ratio between pennies, effervescent tablet, and water are hardly ever the same. The most successful students will only vary one variable and could finish in 20 minutes. They've been used to mentor those groups that are having difficulty. Several students will try to perform the experiment at home before coming in to class.
5. Provided guided questions to the students in terms of experimental design. Try to include vocab/principles in the guided questions ("What does buoyancy have to do with how your sub will work?")
Adaptations:
- Have groups experiment and write the procedure for the successful submarine. The following day, a different group will use the written procedure to execute the submarine. This will reinforce having clear written procedures and the idea that lab results should be repeatable.
- To keep all students working throughout the period, have students experiment and save materials for the official trial. Ten minutes before class ends, run an official trial for all groups all at once to see who is successful so everyone can watch the different methods.
Tips
1. Lab Safety: I do have students wear goggles.
2. Students worry about not having enough effervescent tablets, so they'll have to carefully plan how they will use it.
3. Students do not get their tablet until they show a brainstorm plan. They lose experiment time if they need to create their brainstorm while others begin their lab.
4. There hasn't been a "correct" way to do this. The ratio between pennies, effervescent tablet, and water are hardly ever the same. The most successful students will only vary one variable and could finish in 20 minutes. They've been used to mentor those groups that are having difficulty. Several students will try to perform the experiment at home before coming in to class.
5. Provided guided questions to the students in terms of experimental design. Try to include vocab/principles in the guided questions ("What does buoyancy have to do with how your sub will work?")
Assessment
Oral Assessments:
Student responses to lab design and application questions during the lab.
For example:
- Why did they decide to change the number of pennies and the amount of tablet?
- Why should you have pennies in the container?
- Does it matter how much water you put in?
As a class, we discuss how the sub sinks and floats.
Written Assessment:
Students either fill out the sheet or write a complete lab report, depending on time and other activities we've done.
Lab Execution Assessment:
Students reproduce a successful official trial in front of the teacher.
Student responses to lab design and application questions during the lab.
For example:
- Why did they decide to change the number of pennies and the amount of tablet?
- Why should you have pennies in the container?
- Does it matter how much water you put in?
As a class, we discuss how the sub sinks and floats.
Written Assessment:
Students either fill out the sheet or write a complete lab report, depending on time and other activities we've done.
Lab Execution Assessment:
Students reproduce a successful official trial in front of the teacher.
Standards
9-12.I.B.1. Experimental Design
9-12.I.B.2. Qualitative/Quantitative Data
9-12.I.B.3. Models to Support conclusion
9-12.I.B.2. Qualitative/Quantitative Data
9-12.I.B.3. Models to Support conclusion