Said Slytherin, “We’ll teach just those
Whose ancestry’s purest.”
Said Ravenclaw, “We’ll teach those whose
Intelligence is surest.”

Said Gryffindor, “We’ll teach all those
With brave deeds to their name.”
Said Hufflepuff, “I’ll teach the lot
And treat them just the same.”

About the Hufflepuff part.

A lot of people think that this means that Hufflepuffs have no defining traits.  That we are simply the people the other Houses leave out.  Like being the last one picked for the team in gym class.  Of course, we know from the other Sorting Hat songs that this is wrong.  That there are very specific traits that are associated with Hufflepuff.

And I think this song actually shows one of those traits.  In the disability community, it might be called radical inclusion, although that’s become so much jargon and used for such purposes that I hesitate to use it.

What it means is that everyone belongs.  Nobody gets left out.  Nobody gets given a list of their faults and told “You are the weakest link, bye bye!”  (Which is one of the most chilling lines I’ve ever heard in a game show.)

It means that one of the Hufflepuff values is not leaving anyone out, not if there’s any way to help it.

Of course that has to be done intelligently:  Leaving a serial bully in a community in the name of inclusion, just means you’re excluding hir victims.  

And Hufflepuffs can be prone to forgetting that fact.  Like all values, lots of Hufflepuff values can go really ugly if taken to ideological extremes instead of evaluating based on the situation.  "Including" a serial bully is excluding hir victims, which is not inclusion at all.

But the idea – the vision – of radical inclusion.  Of a place for every student, regardless of their talents.  That is the very opposite of a House having no defining traits.  Radical inclusion is a defining trait of Hufflepuff that is not present in any other House to such a strong degree.  It’s not about being the leftovers, it’s about the entire idea of leftovers being invalid.  It’s about creating a place where the teachers will teach you regardless of what your talents are, regardless of what your disabilities are.

One thing I’ve heard from the best inclusion advocates in the disability rights community is, “If you can tell the ‘regular kids’ from the 'inclusion kids’, you’re doing inclusion wrong, all you’ve got is integration, not inclusion.”  

Hufflepuff at its most ideal best is a place where someone with an intellectual disability can learn right alongside someone without one.  And they will be treated the same in one important way:  The teaching is tailored towards whoever the student is.  They are treated equally, not identically.  And this means that each student is able to get the most learning out of their classes within Hufflepuff.

There’s also, in my headcanon, an ethic among Hufflepuff students where it’s assumed that each student has something to contribute to the other students’ learning.  This means that people who are good at one thing, help people who are not as good at that thing.  And the people who are not as good at that thing, help the others with the things they are good at.  This goes both for school subjects, and for life in general.  There is a general ethic of helpfulness and contributing your abilities to the greater whole, without anyone being put down for lacking abilities in any particular area.

And Hufflepuffs will often team up with Ravenclaws to create assistive technology for disabled wizards, including disabled Hufflepuffs.  

A lot of disabled students end up in Hufflepuff because it’s generally the most disability-friendly of the Houses.  This contributes to some of the ableist stigma that Hufflepuff is stuck with.

At any rate, “I’ll teach the lot and treat them just the same” doesn’t mean leftovers.  It means nobody is leftovers.  It means everyone is valued.  It means treating everyone with the same value, with the same respect, with the same attention to who they really are – not treating everyone identically.  

And that’s one of the best attributes of Hufflepuff, when done right.  Like all House values, some hold to it more than others, and it’s more something to aspire to than something everyone has reached.  But it’s very important, and for some reason very overlooked.