Perhaps the easiest subunit to see and understand on the tape measure, aside from the individual inches, are the half-inch marks. They are exactly halfway between the inch marks. One way of starting this activity might be to challenge students to measure and mark a length on the wooden furring strips of 3 1/2 inches. For more practice, another challenge could be to measure and mark a length of 10 1/2 inches.
After students master the half-inch exercise, another activity can be for them to measure and mark a length on the wooden strips using quarter-inch increments. For example, one challenge would be to measure and mark a length of 3 1/4 inches. Another would be to do a length of 7 3/4 inches. There are four quarters of an inch in one whole inch, and a quarter is half of a half. A verbal explanation of this can be confusing, but the hands-on activity of practicing with the tape measure can make a big difference in teaching and learning these units of measurement.
Moving down to the next level of subunits, have students measure and mark a length along the wooden strip to an increment of an eighth of an inch. For example, one challenge might be to have students measure and mark a length of 5 1/8 inches. Another would be to measure and mark a length of 6 3/8 inches. Of course, any reasonable whole number of inches, in combination with the fraction, is fair game for the activity.
The sixteenth is the smallest subunit on the typical tape measure. And for most carpentry projects measuring things to the nearest sixteenth of an inch is precise enough. The same activities done with the larger subunits provide good practice for working with sixteenths. One activity for using sixteenths on the tape measure is to challenge students to measure and mark the length of 8 7/16 inches.
All the activities using tape measures graduated in inches are adaptable to metric tape measures. A metric tape measure is divided into the metric units centimeters, and each centimeter is subdivided into ten millimeters. So rather that using fractions, a metric measurement uses decimals. For example, a measurement activity might be to measure and mark a length on the wooden strip that is 8.3 centimeters. This would be the eight mark plus three millimeters past the eight mark. Because the metric system is based on multiples of ten, this measurement is equivalent to 83 millimeters.