SummaryStudents create their own simple compasses using thread, needle and water in a bowl — and learn how it works.
Engineers put careful thought into designing compasses that are accurate, precise, durable and inexpensive. To accomplish this, they must thoroughly understand the orientation and strength of the Earth's magnetic field. Scientific concepts such as magnetic declination are important to engineers who design digital compasses that compensate for this effect.
After this activity, students should be able to:
- Explain that a compass is a tool of measurement that shows direction.
- Describe how a compass works.
- Explain that engineers use and develop compasses.
- Explain the relationship between navigation technology and other fields of study (that is, magnetic declination).
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Each TeachEngineering lesson or activity is correlated to one or more K-12 science,
technology, engineering or math (STEM) educational standards.
All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN),
a project of D2L (www.achievementstandards.org).
In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics;
within type by subtype, then by grade, etc.
Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.
All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).
In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.
- Conduct an investigation and evaluate the experimental design to provide evidence that fields exist between objects exerting forces on each other even though the objects are not in contact. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment? Thanks for your feedback!
Each group needs:
- thread, ~12 inches (~30 cm)
- 1 or more packing peanuts (the non-biodegradable type) or other small pieces of Styrofoam™
- 1 plastic bowl (such as a margarine tub) large enough to accommodate the needle
- 1 paper clip
- 2 common straight pins
- Find Your Own Direction Worksheet, one per student
To share with the entire class:
- a few strong magnets
- a few hand compasses
- red or black electrical tape, 1 roll
I have a question for everyone today! What if you were trying to get to your friend's house, and you knew that you needed to head north, but you didn't know which way north was? What would you do to figure it out? (Possible answers: Look at where you are going, follow landmarks, use a map, use a compass.)
Today we are going to talk about compasses. Does anyone know how a compass locates directions? (Collect answers from the class). Do you remember that our planet is one big magnet and has a large magnetic field? Well, a compass is a tool that indicates the magnetic field on the surface of the Earth and determines the direction it is facing based on the magnetic field. A compass is an excellent way to determine how to move in the direction you need to go.
Engineers help design new and improved compasses, including digital compasses and compasses for use in GPS (Global Positioning Satellite) receivers. These engineers definitely have to understand the Earth's magnetic field to accomplish this. Does anyone have any ideas about why an engineer would want to use a compass? Well, engineers use a compass to help them know where a building should be constructed or to determine the direction of a river for a bridge project. Engineers need to make sure that they do the best job they can on their projects, including making sure that a building, or bridge or structure is erected in the right place! The owner of the project would be pretty upset if the engineer messed up, right? So, engineers use compasses and direction to make sure that they build things in the right spot.
Today, we are going to make a simple compass that really works! In fact, you can take your compass home and show your family and friends how it works.
cardinal directions: The four principal directions on a compass: north, south, east and west.
compass: An instrument that uses a magnetized metal bar to indicate the direction of the Earth's magnetic poles.
engineer: A person who applies her/his understanding of science and math to creating things for the benefit of humanity and our planet.
lodestone: A naturally-occurring magnetic rock.
The first compasses were just lodestones — a naturally occurring magnetic ore — on small sticks placed in a bowl of water. This simple device pointed to the pole star and so was used, therefore, for navigation by early mariners. Shortly after the first compasses were used, people discovered that an iron or steel needle that had been touched or rubbed with a lodestone would also align with the pole star.
The Earth's magnetic field has a shape like a strong bar magnet placed near the center of the Earth with its S pole near the north geographic pole and its N pole near the south geographic pole. The Earth's magnetic field, which is three-dimensional, is inclined at about 11 degrees from its axis of rotation. A compass is just a magnet held on top of a pivot so the magnet can rotate freely. A compass points in a direction that lies along the magnetic field at the point. There is also a component of the magnetic field perpendicular to the surface of the Earth.
Before the activity
- Gather materials and make copies of the Find Your Own Direction Worksheet.
- Divide the class into teams of two students each.
- Hand out the worksheets.
With the students:
- Make an X in the center of the outside bottom of the bowl using electrical tape.
- Fill the bowl with enough water (about half way) so that the compass paperclip will be able to move.
- Cut a piece of thread about twice as long as the height of the water in the bowl. Tie one end loosely to a packing peanut. Tie the other end to a paper clip. Make sure the thread is neither too short (it is too short if it pulls the peanut under the water) nor too long (the thread and anchor allows the peanut to float to the sides of the bowl).
- Magnetize the compass "needle" (straight pin) by stroking it one direction with the magnet (you will need to stroke it at least 20 times).
- Stick the compass needle (straight pin) through the center of a packing peanut with the paperclip "anchor."
- Place the pin/peanut/paperclip assembly into the bowl of water (see Figure 1). What happens? (The magnetized straight pin should rotate to be oriented north/south. Verify orientation with a real compass.) Have students record answers on their Find Your Own Direction Worksheets.
- Have students walk around the room with the compass they made. What happens to the compass needle as you move about the room? (Answer: it should always rotate so that it is pointed north/south.) Have students record answers on their worksheets.
- Hold the compass flat near the top of any iron or steel object in the room (the most common steel objects in a classroom are filing cabinets and garbage cans, but any object than contains steel — small refrigerators or radiators, for example — will work). What happens when the compass is near the topmost part of the object? (Answer: the needle should point at the object.) Move the compass down to the bottom of the steel object, still holding it flat. What happens? (Answer: the needle should flip around 180 degrees.)
Remind students to be careful when sticking the pins through the packing peanuts. Peanuts may crumble, making it easy for students to poke their fingers.
Remind students to return their pins to a designated place so they do not get lost or stuck in the carpet.
Students need to stroke the needle in one direction only. Rubbing the needle back and forth will not magnetize it strongly. If they do not stroke the needle enough, it will not be strongly magnetized.
Some students might also realize that the compass and needle point at a direction that is not true north. This is magnetic north. If students are interested, show map and the change in inclination for the compass that can be made to compensate and show true north.
Discussion Questions: Solicit, integrate and summarize student responses.
- What if you knew you needed to head north to get to a relative's or friend's house, but you did not know which way is north? How would you proceed? (Possible answers: Look at where you are going, follow landmarks, use a map, use a compass.)
- How does a compass locate directions? (Answer: A compass indicates the magnetic field on the surface of the Earth and determines the direction.)
Activity Embedded Assessment
Prediction: Ask students to predict what will happen if we float a magnetized needle in water (Answer: The needle will point north.)
Worksheet: The attached Find Your Own Direction Worksheet allows students to record their observations during the activity.
Formation: Have students form a large "X" with groups of students pointing toward the four cardinal directions. Use the compass to resolve any directional disagreement among the students.
Have students conduct research to compare magnetic north and true north. Ask them to identify which they found (magnetic north or true north) in this activity.
Have students investigate more properties of compasses: take the pin and packing peanut assembly out of the water and remove the thread and paper clip. Press another straight pin into each side of the packing peanut. Rest the compass between two drinking glasses with the pins on the rims. What happens?
Use the compass to test an aluminum can. Label the ends of the can with their corresponding magnetic poles and the date. Then turn the can over. Over the next few days use the compass to test the magnetization of the can. When the direction of the magnetization of the can has changed, label the ends of the can with their corresponding poles and the date. How many days does it take for the can's polarity to change?
Have students investigate how electric current affects a compass. Hans Christian Oersted was a science professor in the 1800s who noticed that electric current made the needle of a compass move. Have students research his experiment at: http://www-istp.gsfc.nasa.gov/Education/whmfield.html
For very young students, conduct the activity as a teacher demonstration in front of the entire class.
For lower grades, provide more hands-on help.
For upper grades, have students complete the Northward Ho! activity, which is similar to this activity but for grades 6-8.
Chapman, Michael A. aeroCOMPASS. May 26, 2005. NASA Langley Reserch Center. Accessed December 6, 2006. www.nasa.gov/centers/langley/home/index.html
ContributorsJeff White; Matt Lippis; Penny Axelrad; Janet Yowell; Malinda Schaefer Zarske; Abby Watrous; Jay Shah
Copyright© 2006 by Regents of the University of Colorado
Supporting ProgramIntegrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder
The contents of this digital library curriculum were developed under grants from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education, and the National Science Foundation (GK-12 grant no 0338326). However, these contents do not necessarily represent the policies of the DOE or NSF, and you should not assume endorsement by the federal government.
Last modified: August 10, 2017