6 years & up. Introduce your children to magnetism with this Mysterious Magnet Tube with Iron Filings for Interactive Science Concepts. This magnetic tube has a cow magnet which slides up and down inside a plastic tube. Inside, the container is filled with iron filings. Children will be amazed at how the iron reacts to the magnet. Use this tube for an interactive lesson about the properties of magnets. Encourage your children to ask questions about concepts they?re unfamiliar with.