Try these two resources --
20 Prayer Lessons for Children
20 More Prayer Lessons for Children
Both by Phyllis Vos Wezeman and Jude Dennis Fournier. Both published by Twenty-Third Publications.
Also, look for the "Worship for Life' curriculum developed by Phyllis and a team of volunteers here at Rotation.org and published by LOGOS circa 2007.
It is now known as the "God's People Worship" curriculum and is available at https://www.genonministries.or...-gods-people-worship It has spiritual practices and prayer built-in to its curriculum.