This article from Edutopia gives four concrete ways that one could incorporate mindfulness into the classroom. As the article recommends, begin these practices with yourself first. It is helpful to understand what happens during a mindfulness practice before asking your students to do it.
In learning about mindfulness, you find that it is helpful for teachers to use guided meditations. Here there are quite a few guided meditations and classroom activities that cultivate mindfulness in the classroom.
Teaching mindfulness can be tricky, especially when you are dealing with children. In this resource, there are specific tips and tools that you can try in your classroom to prepare students for a more mindful experience in learning.
Mindful Schools is a resource for teachers and students alike. This page has a video that shows children talking about the benefits of meditation. At the bottom there are a few guided practices that teachers can use to increase their own mindfulness and tips to bring to the students. This also provides professional development for educators at an additional cost to become certified mindfulness instructors for faculty and students.
This is a great resource to start for mindfulness. In order to teach mindfulness, it is important that educators have their own practice. This resource provides activities and guidelines, and explains the importance of mindfulness in the classroom.