Abstract: Methods for forming chemical and/or biological products in reactors, and/or analyzing chemical and/or biological interactions in reactors are provided. The methods relate, more specifically, to forming such products and/or carrying out such analyses in small volume reactors with control over overall fluid volume in the reactors. The methods can be used to mimic processes in large scale reactors and/or to obtain reaction or interaction information relevant to large scale reactors (e.g., to adjust/optimize large-scale reactor processes). Advantageously, the methods can allow parameters of small scale reactors to be correlated with those of large scale reactors, where desired.