I ask students to think silently for a few minutes about all the different places that they've seen or heard about magnets being used, in addition to the magnets we use to hold papers on the refrigerator, magnetic whiteboards, and so on.
Then they share out to the class and I list the examples in a Google doc as they give them. If students use examples similar to magnets on a whiteboard, I list it, but group them together. In my class there were several unexpected examples.
I show the students the first 2:20 minutes of this video on How Magnets Work. It's from 1954 and they enjoy the style difference. Anyhow, it presents a very simple and visual example of how electrons move when there is a magnetic force on certain materials. It's not something they need to understand in 3rd grade but they find it interesting, and it plants the seed of the idea that electricity and magnetism involve forces acting at the atomic level, not just large magnets smashing into each other in our classroom.
Next, I show them this clip that shows how magnets are used as brakes on a rollercoaster. I ask them to draw and label a diagram that explains how the magnets are used used to stop the roller coaster.
Then I have them engage with this clip that shows an electromagnet and they draw and label a diagram of how this magnet is used.
I have them discuss their diagrams and how these two uses are different from one another with a small group.
Then, to get them thinking about other ways magnets might be used, and additional uses they could come up with for magnets, I show them these two "extreme" examples of magnet forces interacting with other objects.
This video clip shows super strong neodymium magnets crushing ordinary objects. I do not let them see the website address at the end, even though none of them could order the magnets without their parents' help. This example shows how magnetic coils can melt metal. Finally, here's a relatively recent discovery with a magnet that both repels and attracts another magnet. How could this be used?
For children who are interested or need enrichment, here is a clip from Discovery Education, available on YouTube, explains how magnets are made. Again, not 3rd grade content, but I like to provide it to students who are interested.
I ask students to write down one new understanding from today and one new question. They put this in their science notebook and I ask them to share it with someone at home tonight.