Science Lesson Kit · Teacher Resource
Earth's Magnetic Field: Why Does a Compass Point North? — 5E Lesson Plan
Earth Science · 50 minutes
Grade 4
5E lesson flow
01
Engage
6 min
Teacher Does
Turn the compass case while allowing the needle to settle.
Students Do
Notice the needle's direction and write a prediction.
Ask
- What stays nearly the same as the case turns?
Look For
Recognize that the needle responds to a field, not the printed N.
02
Model
9 min
Teacher Does
Show Earth's approximate field and explain true versus magnetic north.
Students Do
Use a picture to explain why the needle turns.
Ask
- Does a compass seek geographic north exactly?
Look For
Distinguish magnetic alignment from map labels.
03
Navigate
9 min
Teacher Does
Orient a simple grid map north-up and model a short route.
Students Do
Trace east, north and west legs and check endpoints.
Ask
- What changes on a grid when we move east?
Look For
Accurate cardinal movements and endpoint reasoning.
04
Investigate
13 min
Teacher Does
Supervise baseline/near/far observations with one magnet.
Students Do
Record needle behavior and compare with a wooden stick control.
Ask
- What was changed? What stayed the same?
Look For
Describe a fair comparison and repeat baseline.
05
Reason
7 min
Teacher Does
Discuss interference and declination without requiring bearings arithmetic.
Students Do
Use evidence to recommend a reliable compass reading.
Ask
- How do we know a local object affected the needle?
Look For
Explains that field interference is local.
06
Assess
6 min
Teacher Does
Distribute the independent Pine Ridge worksheet.
Students Do
Solve a novel map and explain a new interference case.
Ask
- What have we learned and what is uncertain?
Look For
Distinguish field direction from map north.
Student goal
I can model why a compass turns, read a four-direction map, and test whether a nearby object changes a reading.
Learning objectives
- Use a compass model to explain how a magnetized needle aligns with the direction of Earth's local magnetic field.
- Follow cardinal directions to map a short route and distinguish magnetic north from true north.
- Collect evidence about how nearby magnets or steel can change a compass reading and explain limits of the model.
Materials
- At least one sturdy classroom compass per group
- Nonmagnetic pencils and paper
- Teacher-approved small bar magnets
- Wooden craft sticks
- Printed grid maps
- Flat tabletop
- Ruler
Before class
- Confirm each compass needle moves freely on a flat surface.
- Mark a safe station away from computers, tablets and large metal surfaces.
- Precheck if desks contain steel parts; move to nonmetallic surface if needed.
- Prepare map cards assuming compass north equals grid north for grid practice.
- Tell students the difference between a local reading and real-navigation requirements.
Safety & supervision
Review these precautions before students begin the investigation. Follow your school's safety procedures.
- Never put strong magnets near medical implants or personal electronic devices.
- Use small, intact classroom magnets; keep away from mouth and eyes.
- Do not use loose tiny magnets and do not open magnet-containing toys.
- Do the investigation away from electronics and metal furniture; follow school magnet-safety policy.
Prior knowledge
- Magnets can exert forces without touching.
- Map directions include north, east, south and west.
Vocabulary
- magnetic field
- An invisible region around a magnet, or Earth, where magnetic forces can act.
- compass
- A tool with a magnetized pointer that turns to line up with a magnetic field.
- magnetic north
- The direction a compass shows when guided by Earth's magnetic field at your location.
- true north
- The direction along Earth's surface toward the geographic North Pole.
- declination
- The angle between magnetic north and true north at one place.
- cardinal directions
- North, east, south and west, the four main map directions.
- interference
- When a nearby source of magnetism changes a compass reading.
Differentiation
- Provide a large directional floor mat and move a marker.
- Allow a tactile or enlarged compass rose.
- Use a worked example of how x/y grid steps change.
- Extension: locate current declination on a current area map, with adult support.
Assessment
- Check grid route and compass rose.
- Review recorded baseline and control.
- Ask for a scientific explanation of declination.
- Compare independent worksheet responses with answer key.
Exit ticket
What tells a compass needle where to point, and what nearby object might cause trouble?
Extension
Use an up-to-date topographic map's declination diagram to discuss why a real hiker may need to correct bearings.