A method of making a crystalline molecular sieve of MFS framework type, preferably ZSM-57, from a synthesis mixture comprising at least one source of tetravalent element (Y), at least one source of trivalent element (X), at least one source of alkali metal hydroxide (MOH), at least one structure-directing-agent (R) and water, said alkali metal (M) comprising potassium, and having the following mole composition (expressed in terms of oxide): YO2:(p)X2O3:(q)OH−:(r)R:(s)H2O, wherein (p) is in the range from 0.005 to 0.05, (q) is in the range from 0.01 to 3, (r) is in the range from 0.03 to 2 and (s) is in the range from 10 to 75 (based on total weight of said synthesis mixture); wherein the crystals of molecular sieve formed having an average diameter (D) of less than or equal to 1.5 micron and an average thickness (T) of less than or equal to 300 nanometers.