Which expression is equivalent to the expression - 2/3 (3 - 1/2) (-1) ?

The fraction 1/3 means 1 out of 3 equally divided parts, so 12 needs to be equally divided into 3 groups. Have students divide the 12 stars into 3 equal groups. Each of the 3 equally divided groups is 1/3 of the total. Thus, 1/3 of 12 is the number in 1group, or 4.