Apple has partnered with Common Sense Media to curate collections of podcasts for kids in the US. The shows are picked by Common Sense Media, an organization whose editors have a long history of helping parents and educators find age-appropriate media for children.
The collections are only visible in iTunes, and I couldn’t find the list outside of it. But, this doesn’t mean you have to use iTunes to listen to the Podcasts. You could use iTunes to find podcasts and then share a link to the podcasts’ websites with your students.