1. Have your partner pick an object in the room greater than 10 ft away.
2. Look at the object in question then look at the measuring tape. Repeat 2-3 times.
3. Approximately judge the size of the object by saying out loud how tall the object is. Now walk up and compare your measurement to that of the object. Repeat several times with different objects.
4. Do not look at either the object or the measuring tape for a long period of time. Instead, take short looks between the object and the measuring tape.
5. Have your partner tell you when you're misjudging the size (too big or too small).