ELEMENTARY SCHOOL PUPILS' ABILITY TO USE EVIDENCE FROM SCIENTIFIC INSTRUMENTS WAS DETERMINED. THE 320 PUPILS FROM GRADES ONE THROUGH SIX WERE PLACED IN DECISION-MAKING SITUATIONS REQUIRING THEM TO USE EVIDENCE FROM A PLATFORM BALANCE OR GRADUATED CYLINDER. PUPILS WERE REQUIRED TO DIFFERENTIATE BETWEEN MASSES OR VOLUMES OF PAIRS OF OBJECTS. THE FIRST ATTEMPT WAS BY VISUAL OBSERVATION OF THE OBJECTS. THE SUBJECTS WERE THEN ALLOWED TO OBTAIN EVIDENCE BY USE OF THE APPROPRIATE INSTRUMENT AND ASKED TO DIFFERENTIATE BETWEEN THE MASSES OR VOLUMES AGAIN. WHEN THE STUDENTS PROVIDED THEIR ANSWERS, THEY INDICATED CONFIDENCE IN THEIR DECISION BY WAGERING FROM ONE TO TEN POINTS. THE NUMBER OF POINTS WAGERED AFTER THE STUDENTS HAD OBTAINED EVIDENCE FROM THE INSTRUMENT WAS COMPARED TO THE NUMBER OF POINTS WAGERED BY THE STUDENTS IN THEIR INITIAL RESPONSES. RESULTS OF THE INVESTIGATION INDICATED THE FOLLOWING. (1) IQ DID NOT HAVE A SIGNIFICANT RELATIONSHIP TO THE ABILITY TO USE EVIDENCE FROM A SCIENTIFIC INSTRUMENT. (2) STUDENTS DID NOT IMPROVE IN ABILITY TO USE EVIDENCE FROM A SCIENTIFIC INSTRUMENT FROM ONE GRADE TO THE NEXT. ERRORS WERE HIGH IN GRADE ONE, DECREASED IN GRADES TWO AND THREE, INCREASED IN GRADE FOUR, REACHED A MAXIMUM IN GRADE FIVE, AND DECREASED IN GRADE SIX. (3) THE OPPORTUNITY TO MANIPULATE THE OBJECTS AND THE INSTRUMENTS DID NOT RESULT IN IMPROVED PERFORMANCE. THIS DOCUMENT IS AVAILABLE AS ORDER NUMBER 66-6283 FOR $3.00 ON MICROFILM, $6.40 XEROGRAPHY, FROM UNIVERSITY MICROFILMS, 300 NORTH ZEEB ROAD, ANN ARBOR, MICHIGAN 48103. (RH)