Position terms can be quite subtle for many of our students. For example nine and ninth. One word refers to a finite quantity of 9 objects, the other to the position of an object in a line that starts at 1 and continues to at least 9 places. There are 8 objects before or in front of it and perhaps there are objects behind it too. It is a relationship to other objects not a quantity in itself.
The calendar is packed with position language. Days, weeks and months fit together in a continuous cycle. Nine can be the 9th day of a particular month, the ninth month of a particular year or the ninth year of a particular group of years.
And did you know that in the ninth month 26 September is the only day of the year that is written the same as its position number – 26/9 – 269th day – but not in a leap year (the next leap year is 2020). Amazing.