Explanation of test items ᔡ 215
(i) Ted’s penknife is a very heavy one. His key is not a fairly heavy one and cannot be very heavy because he already has a heavy object, his penknife, so it must be light, and, therefore, it must be the book that is fairly heavy. (ii) Ted’s book, Rick’s penknife and John’s key are all described the same way so, as it has been established that Ted’s book is fairly heavy, the others must be too. (iii) Rick’s book and John’s penknife are the same weight. John’s penknife must be the light one because the fairly heavy one belongs to Rick and the very heavy one to Ted. (iv) These are the only remaining possibilities that can complete the matrix, giving each boy the same objects each with three different weights.