Here, we describe a platformed “jump board” strategy and its application in systematically engineering the essential microRNA let-7 (Fig. 1A-E) and protein coding gene lin-28 (Fig. 1F) in C. elegans. We chose the jump board protospacer sequence (INPP4A) which is (1) comprised of a PAM site and a protospacer antisense to a crRNA with experimentally confirmed high editing efficiency (INPP4A-crRNA), and (2) non-homologous to C. elegans genome, including the genetic balancer we used (mnDp1). Notably, the jump board protospacer contains an EcoRV restriction site, which can be utilized for rapid large-scale genotyping by which HDR events can be identified in the F1 generation (Fig. 1C). Using the jump board strategy, we have so far created 28 let-7 alleles for various experimental purposes, among which 15 alleles showed lethality and require rescue by mnDp1. Note that the let-7 jump board allele (ma393) itself is a new let-7 null allele in which the precursor-let-7 is completely removed.