Week 6: We built our own compasses and did an activity to learn more about the Earth's magnetic field.
The Earth's magnetic field is generated by the liquid iron continuously flowing in the core. Today our compass needles point north, but it hasn't always been that way. Scientific evidence found in pottery, Hawaiian volcanic lava flows and ancient lava flows suggest the Earth's magnetic field changes direction every 200,000 years or so. Being that it's been over 700,000 years since the last reversal, we are overdue for a flip.
The magnetic field protects us from the sun and from solar weather. Without it, solar weather would bombard our planet with radiation and strip away the atmosphere as it has done to Mars. On the positive side, the gorgeous northern lights are visible reminder of the magnetic field. If the magnetic field does change directions during our lifetime, the northern lights would be visible all over the planet.
The kids were glued to the screen during the video "Will the Earth's Magnetic Field Shift?" and so was my husband. This film not only explained how the magnetic field works, but gave plenty of explanation as to how it has behaved in the past and is expected to behave in the future.
Since the interaction between the magnetic field and solar radiation is responsible for the northern lights, we couldn't resist a few extra short videos.
This video explains how the northern lights are generated.
In addition to explaining the northern lights, this short video also discusses several legends associated with the Aurora Borealis.
Playing with Magnets
After learning about the magnetic field, we played with magnets.
Earth's Core and Magnetic Field in a Bottle
Next, using steel wool, cooking oil and an empty water bottle, we made a fun toy which represented the Earth's core and the magnetic field.
With scissors, the steel wool was cut into smaller pieces.
A water bottle was filled with cooking oil.
Then the steel was put into the oil.
The kids placed magnets near the bottle to explore what would happen.
The magnets act like the Earth's core and the steel pieces are like the magnetic particles of the magnetic field. By moving the magnets, the field adjusts.
Making a Compass
It is surprisingly easy to make a compass. All that's needed is foam or something that floats and a pin can stick into, a magnet, a pin and a container with water.
The first and most important step is to magnetize the needle. This is done by rubbing it with the magnet 50 to 100 times in the same direction.
Then the needle is stuck into the foam and placed in water so that it can move about freely. We found that a large container of water worked best as the compass tended to move against the side with a smaller container.
It didn't look that pretty, but it worked. Time and again the kids were able to move the compass in the water and watch while it repositioned itself to point north.
Great experiment - love your hands on approach with the kids! Fantastic!
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