AnOS 1 is an experimental operating system kernel built from the ground up for both education and research. Compared to other similar kernels, AnOS is unique in three aspects: 1) ARM-centric in light of a recent shift of computing from x86 to ARM; 2) microkernelbased given a resurgent interest in microkernel from industry; 3) bimodal for both education and research such that students can easily switch from learning to researching. This paper will describe our three-year experiences in teaching and experimenting operating systems with AnOS.