The lesson explains how to magnetize an object using the stroke method, which involves moving a permanent magnet’s pole over the object about 20 times in the same direction. The concept of magnetic poles is demonstrated using an experiment with magnets stacked on a wooden rod; when some magnets are turned and replaced, they float due to the repulsion between like poles. This illustrates the principle that like poles repel, emphasizing that the top of magnet 4 repels the bottom of magnet 5 because they have the same poles, either both north or both south.