Why do real estate agents post school districts by number?

We're looking up houses and I can't figure out what school districts some of the houses are in. How do you know what school district is what number? Anyone know if there is a website to look up school districts by number?

Thanks

I know I saw a thread about this a while ago... I just found it... It's not complete, but maybe you can FM the one who wrote it (Misha)

It is so annoying that they do that.. but it's probably because they want to downplay the importance of which district the house is in if it's not such a good one.

1 Elwood
2 Syosset
3 Huntington
4 Northport
4 Plainview
5 Levittown
5 Dix Hills/Half Hollow
6 Huntington Harborfields
6 Amityville
10 Commack
13 South Huntington
17 Hicksville
18 Plainedge
21 Bethpage
22 Farmingdale
23 Massapequa
26 Island Trees

from this threadthread

Hope this helps!