GK-12 Sensors!
Portable Module

Title: Measuring Flow

Author: Edwin Nagy

Discipline: 9th Grade Physical Science

Introduction

This module is designed to introduce students to the concepts of viscosity and pressure head, as well as providing a vehicle for discussion of different types of fluids: suspensions, solutions, mixtures, etc.

Associated Maine Learning Results

SCIENCE AND TECHNOLOGY (Secondary Grades)

E. STRUCTURE OF MATTER
Students will understand the structure of matter and the changes it can undergo. Matter is made of atoms, each with characteristic properties, which can combine to form all substances in the universe. The state and properties of matter may differ when it experiences chemical, physical, and nuclear changes.

J. INQUIRY AND PROBLEM SOLVING
Students will apply inquiry and problem-solving approaches in science and technology. Scientific inquiry, problem solving, and the technological method provide insight into and comprehension of the world around us. A variety of tools, including emerging technologies assist, the inquiry processes. Models are used to understand the world.

Specifically students will:
• Make accurate observations using appropriate tools and units of measure.
• Verify, evaluate, and use results in a purposeful way. This includes analyzing and interpreting data, making predictions based on observed patterns, testing solutions against the original problem conditions, and formulating additional questions.

MATHEMATICS (Secondary Grades)

C. DATA ANALYSIS AND STATISTICS
Students will understand and apply concepts of data analysis. We are faced with massive quantities of information which must be selected, sorted, and analyzed to reach conclusions. Sound decision making requires the ability to collect data effectively, organize data, discover patterns, summarize trends, make inferences, draw conclusions, and make predictions. The ethical use of statistics is a paramount concern in the Information Age.

F. MEASUREMENT
Students will understand and demonstrate measurement skills. Measurement is valuable as an integrating skill throughout the curriculum and in everyday life. The use of estimation is vital in determining the reasonableness of measurement. Measurement attributes (e.g., length, volume, minutes), units, and tools enhance the ability to describe and understand the world.

Specifically, students will:
• Use measurement tools and units appropriately and recognize limitations in the precision of the measurement tools.
• Derive and use formulas for area, surface area, and volume of many types of figures.

Required Equipment

*Per lab group
**Per lab station

Procedures

This is a one-day (45 minute) module with follow-up classroom discussion, or a 2-period module. The initial presentation should take about 5 minutes, and the experiment itself will generally require an additional 35-40 minutes to complete. Discussion of class-wide results and variation therein should be a significant portion of the educational value of the lab.

1. Initial presentation

1. Present the idea of viscosity and flow.
2. Present the lab procedure, stressing the importance of consistent measurements between stations and within a set of trials.

2. Flow testing

1. Set up any number of stations, each with its own fluid. If there are some very slow fluids, it may be worthwhile to set up two (or more) identical stations so that the students measuring the slow fluids can spend more time with them without creating a traffic jam. Each station consists of a container of a fluid, a funnel with attached hose, a catch bucket and a stop watch.
2. Students, working in groups will go to a station, and following directions on the lab sheet, fill the hose and funnel with the fluid so that the fluid is above the top line. One student will then unclip the binder clip from the end of the hose and allow the fluid to start draining out into the catch bucket. The timing student should watch the fluid level, and when it gets down to the top line, start timing. When it gets to the bottom line, the student should stop timing. The clipping student might want to clip the hose again at this point to avoid having to fill the entire hose again. Five measurements should be taken at each station.
3. Additional stations can be set up using the same fluids, but having a different height difference between the top of the funnel and the bottom of the hose. Additionally, stations could be set up with shorter straight hoses and longer hoses with loop-di-loops, or even two hoses of the same length but where one slopes down continually and the other goes in a loop but has the same net height difference.

3. Discussion items

1. What effects the fluid flow time?
2. Why are some fluids more viscous than others?
3. What effect do hose length, height difference and hose loopiness have on flow times. Are these effects different for differently viscous fluids?
4. What do some groups’ responses for a given station differ drastically from others (if they do)? Why is there variation within a group’s measurements at one station? How could these be avoided?
5. What is the correct way to average a series of times of the form mm:ss (e.g. 3minutes and 12 seconds)?

Expected Results

Students should gain an understanding of the importance of measuring techniques and response time – e.g. the difference in time between when one student says, “go” and when another starts timing, and the difference between looking horizontally at a measurement line and looking down at it. Students should gain an appreciation for the wide range of viscosities on common fluids. If a microwave is present, students could also examine and understand the effect of heat on viscosity for some fluids, but not (measurably) for others.

Troubleshooting

Messy, messy, messy! Make sure that lab surfaces are easy to clean and that cleaning supplies are at hand. Students also tend to try to “cheat” by raising the funnel higher for the slow fluids in order to make them go faster. (This should be obvious in the final results.) In addition, there is the danger of contamination of fluids with water if the students are so inclined. Otherwise, this is a fairly robust experiment.

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