Yannick's class measured the width of one leaf serval times the values that the class recorded included 10 mm 8 mm 15 mm 5 mm 13 mm. The several different widths indicate that the class lacked the understanding of the word 'width' of the leaf and a standard procedure to make the measurements. Since leaf has two axis of making measurements, along the vein and across the vein. The measurements made along the vein would be greater than that of the across the leaf stem. Also the point of measurement of the width across the vein would vary as leaf tappers by the tip. Hence they should have been instructed to measure the width across the vein by folding the leaf into two halves, so as to make the readings more relevant.
