How to is the challenge but consider this idea. Presenting to entire faculties, esp. elementary that meditation has applicable good for the child. Over time and ritual of attending to the process the child could gain immeasurably by the practice of meditation.. Just the silent ritual practiced every day.. not prayer... but concentrated silence.. An idea worth exploring.. Even intro to a faculty by a silent 4-5 minutes of silence and thoughts.. Teachers would love the practice .
Mindful schools has a great curriculum on how to do this - it starts with very brief lessons and you are right on about practicing every day and it being a whole school activity. Some schools have mindful minutes. Also please note the critical importance of people understanding how to do this with SAFETY in mind! That is, this practice can trigger students (and staff) with trauma histories. The best book I have read so far on this topic is called Trauma sensitive mindfulness by Michael Trelevean...there are also some good articles online like this one Nine ways
You might look at Mind Matters as a way to bring mindfulness and other trauma healing practices to schools to adults and students alike. People are using the materials with children down to the 4th grade ("Calm Coaches" and up into high school, including alternative settings plus teacher professional development. Happy to send you a complimentary, online review copy because it's always good to see it for yourself. (Note: The Dibble Institute publishes Mind Matters.)
Inner explorer is a guided meditation program I used successfully in my classroom last year.