Miraculous Marangoni Soap Boat
15-30 min
Ages 8+
What Will You Make?
Make a classic Victorian toy that moves thanks to surface tension. We’ll start with a traditional paper version and then craft our own plastic version.
What Will You Learn?
In this activity, we’ll explore surface tension, the Marangoni effect, and forces and motion.
Create Your Toys
Paper Fish
Here’s an update of a Victorian plaything. Cut out the fish on the dotted line and float it on a pan of water. Place a single drop of olive oil in the circle. The oil quickly spreads out the slit and across the water. The fish “swims” in the opposite direction, like an exhaust-spewing rocket subject to Newton’s third law of motion. Sadly, the soggy paper fish is only good for just a single use (Figure A).
Durable Boat
Find a flexible lid from a margarine or yogurt container. Look for the recycling symbol 2 or 4 for low- or high-density polyethylene. (PE is one of the few plastics that floats.) Use a paper punch to make a small circular hole, then cut out the “rocket” shape as shown in Figure B.
Float the rocket in a pan of clean water. Dip the tip of a toothpick in detergent and momentarily touch it inside the rocket’s round hole. As the detergent dissolves, it spreads down the slit and out along the surface of the water — the rocket shoots forward! Touch it again. After a time or two, you’ll have to change the water for the effect to work again.
What Is Happening Here?
Marangoni effect
As the detergent dissolves, it spreads down the slit and out along the surface of the water — the rocket shoots forward.
Another force is also at work: the Marangoni effect, the difference in surface tensions created by the molecules of detergent as they make the water slipperier and “wetter.” The surface tension is reduced behind the rocket, causing the water in front to contract, pulling the rocket forward (Figure C above).
These tensions, forces, and actions all exist at the single-molecule-thick surface of the water — similar to the two-dimensional world in Edwin Abbott’s Victorian-era book, Flatland: A Romance of Many Dimensions.
What' Next?
Toy Inventor's Notebook
Why not try making more classic toys? Try these ideas from Make: Magazine!
This project originally appeared in Make: Magazine in October 2020. The author is Bob Knetzger. Bob is an inventor/designer with 30 years of experience making fun stuff.
Materials:
- Paper
- Pencil
- Scissors
- Paper punch
- Toothpick
- Margarine or yogurt container top
- Pan for water
- Water
- Oil
- Dish detergent
Maker Camp Project Standards
Based on NGSS (Next Generation Science Standards)
National Core Arts Standards
The National Core Arts Standards are a process that guides educators in providing a unified quality arts education for students in Pre-K through high school. These standards provide goals for Dance, Media Arts, Music, Theatre, and Visual Arts with cross-cutting anchors in Creating, Performing, Responding, and Connecting through art. The Anchor Standards include:- Generate and conceptualize artistic ideas and work.
- Organize and develop artistic ideas and work.
- Refine and complete artistic work.
- Select, analyze, and interpret artistic work for presentation.
- Develop and refine artistic techniques and work for presentation.
- Convey meaning through the presentation of artistic work.
- Perceive and analyze artistic work.
- Interpret intent and meaning in artistic work.
- Apply criteria to evaluate artistic work.
- Synthesize and relate knowledge and personal experiences to make art.
- Relate artistic ideas and works with societal, cultural, and historical context to deepen understanding.
CCSS (Common Core State Standards)
The Common Core is a set of high-quality academic standards in mathematics and English language arts/literacy (ELA).English Language Arts Standards » Science & Technical Subjects
- Middle School
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- CCSS.ELA-LITERACY.RST.6-8.1 Cite specific textual evidence to support analysis of science and technical texts.
- CCSS.ELA-LITERACY.RST.6-8.3 Follow precisely a multistep procedure when carrying out experiments, taking measurements, or performing technical tasks.
- CCSS.ELA-LITERACY.RST.6-8.4 Determine the meaning of symbols, key terms, and other domain-specific words and phrases as they are used in a specific scientific or technical context relevant to grades 6-8 texts and topics.
- CCSS.ELA-LITERACY.RST.6-8.5 Analyze the structure an author uses to organize a text, including how the major sections contribute to the whole and to an understanding of the topic.
- CCSS.ELA-LITERACY.RST.6-8.6 Analyze the author's purpose in providing an explanation, describing a procedure, or discussing an experiment in a text.
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- High School
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- CCSS.ELA-LITERACY.RST.9-10.1 Cite specific textual evidence to support analysis of science and technical texts, attending to the precise details of explanations or descriptions.
- CCSS.ELA-LITERACY.RST.9-10.3 Follow precisely a complex multistep procedure when carrying out experiments, taking measurements, or performing technical tasks, attending to special cases or exceptions defined in the text.
- CCSS.ELA-LITERACY.RST.9-10.4 Determine the meaning of symbols, key terms, and other domain-specific words and phrases as they are used in a specific scientific or technical context relevant to grades 9-10 texts and topics.
- CCSS.ELA-LITERACY.RST.9-10.5 Analyze the structure of the relationships among concepts in a text, including relationships among key terms (e.g., force, friction, reaction force, energy).
- CCSS.ELA-LITERACY.RST.9-10.6 Analyze the author's purpose in providing an explanation, describing a procedure, or discussing an experiment in a text, defining the question the author seeks to address.
- CCSS.ELA-LITERACY.RST.11-12.1 Cite specific textual evidence to support analysis of science and technical texts, attending to important distinctions the author makes and to any gaps or inconsistencies in the account.
- CCSS.ELA-LITERACY.RST.11-12.3 Follow precisely a complex multistep procedure when carrying out experiments, taking measurements, or performing technical tasks; analyze the specific results based on explanations in the text.
- CCSS.ELA-LITERACY.RST.11-12.4 Determine the meaning of symbols, key terms, and other domain-specific words and phrases as they are used in a specific scientific or technical context relevant to grades 11-12 texts and topics.
- CCSS.ELA-LITERACY.RST.11-12.5 Analyze how the text structures information or ideas into categories or hierarchies, demonstrating understanding of the information or ideas.
- CCSS.ELA-LITERACY.RST.11-12.6 Analyze the author's purpose in providing an explanation, describing a procedure, or discussing an experiment in a text, identifying important issues that remain unresolved.
NGSS MS.Engineering Design
The Next Generation Science Standards (NGSS) are K–12 science content standards.- MS-ETS1-1. Define the criteria and constraints of a design problem with sufficient precision to ensure a successful solution, taking into account relevant scientific principles and potential impacts on people and the natural environment that may limit possible solutions.
- MS-ETS1-2. Evaluate competing design solutions using a systematic process to determine how well they meet the criteria and constraints of the problem.
- MS-ETS1-3. Analyze data from tests to determine similarities and differences among several design solutions to identify the best characteristics of each that can be combined into a new solution to better meet the criteria for success.
- MS-ETS1-4. Develop a model to generate data for iterative testing and modification of a proposed object, tool, or process such that an optimal design can be achieved.
NGSS HS.Engineering Design
The Next Generation Science Standards (NGSS) are K–12 science content standards.- HS-ETS1-1. Analyze a major global challenge to specify qualitative and quantitative criteria and constraints for solutions that account for societal needs and wants.
- HS-ETS1-2. Design a solution to a complex real-world problem by breaking it down into smaller, more manageable problems that can be solved through engineering.
- HS-ETS1-3. Evaluate a solution to a complex real-world problem based on prioritized criteria and trade-offs that account for a range of constraints, including cost, safety, reliability, and aesthetics as well as possible social, cultural, and environmental impacts.
- HS-ETS1-4. Use a computer simulation to model the impact of proposed solutions to a complex real-world problem with numerous criteria and constraints on interactions within and between systems relevant to the problem.
NGSS 3-5.Engineering Design
The Next Generation Science Standards (NGSS) are K–12 science content standards.- 3-5-ETS1-1. Define a simple design problem reflecting a need or a want that includes specified criteria for success and constraints on materials, time, or cost.
- 3-5-ETS1-2. Generate and compare multiple possible solutions to a problem based on how well each is likely to meet the criteria and constraints of the problem.
- 3-5-ETS1-3. Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved.
