Focussing on a topic for a long time becomes challenging for both kids and adults. However, it’s more difficult in the case of the latter as they get easily distracted by anything and everything in their surroundings. Although Augmented Reality (AR) educational applications enhance motivation, interest, kids still face usability issues of smaller screen size, complex functionality, device handling, etc. The literature lacks the usability principles for handheld AR applications for young users (kids). To address the gap, this article introduces twenty three principles to be considered for developing AR applications for young learners. An Augmented Reality Learning Environment (ARLE) kit for teaching basic language skills is developed using the proposed principles. A comprehensive approach including qualitative and quantitative analysis was deployed to analyse the effectiveness, efficiency and usability of ARLE. The survey from 30 kindergarten kids and their 12 teachers indicated that the proposed ARLE is effective, efficient, usable for the young learners. It can be concluded that the proposed usability principles could be referred to by designers, educators, researchers, developers when designing AR applications for young kids.