Check out these "Odd One Out" worksheets which are specifically designed so that children learn logical reasoning and the concept of categorization. Children are presented a number of objects out of which they have to identify and circle the odd one out in each row.
Tips for Parents/Teachers: Use these Odd One Out worksheets to develop logical reasoning skills by initiating a discussion on the properties of each object in the row and how one of them is different than others. That way, after enough odd one out examples they themselves can identify the odd one in the group.