The invention provides methods, compositions and kits for generating a signal indicative of the presence of a target nucleic acid sequence in a sample comprising forming a cleavage structure by incubating a sample comprising a target nucleic acid sequence with upstream and downstream oligonucleotides, and cleaving the cleavage structure with a nuclease to generate a signal. The presence of a detectable signal is indicative of the presence of a target nucleic acid sequence and a non-invasive cleavage structure.