IMPLEMENTASI MODEL PEMBELAJARAN KOOPERATIF TIPE NUMBERED HEADS TOGETHER (NHT) UNTUK MELATIHKAN KETERAMPILAN BERPIKIR KRITIS SISWA PADA MATERI STOIKIOMETRI DI SMAN 3 LAMONGAN (IMPLEMENTATION OF COOPERATIVE LEARNING MODELS NUMBERED HEADS TOGETHER (NHT) TYPES TO TRAINING STUDENTS’ CRITICAL THINKING SKILL ON STOICHIOMETRY MATTER IN SMAN 3 LAMONGAN) - MUFIDHATUR ROHMAH, DATIN (UNESA Journal of Chemical Education, 2015)