Learning the Lord’s prayer requires understanding “forever and ever”.
Lance Rips, Amber Bloomfield and Jennifer Asmuth write about how children learn math concepts including infinity. This gives us some idea of how children may learn the Lord’s Prayer as well.
Citation for paper.
Rips, L. J., Bloomfield, A., & Asmuth, J. (2008). From numerical concepts to concepts of number. Behavioral and Brain Sciences, 31,623-642.
The concept of the infinite is a key concept in the ending of the Lord’s Prayer. The succession of days is a basic part of the concept framework of faith. These concepts and how children learn or relate to them in learning math is discussed in the above paper. This can be a fruitful line for those trying to develop a better understanding of this, develop a lesson, or write a sermon.