Examine the magnet closely for comparison to what you will observe later. Place the cereal and the magnet in the bag and gently shake for 5 minutes. Remove the magnet and observe. You will find small bits of iron stuck to the magnet. Scrape off the bits onto a piece of white paper and place the magnet under the paper to show that it is not just bits of cereal.
Iron ore is concentrated by using magnets to remove the ore from the accompanying minerals.