Hi Andy

Magister : It's a well known and regular holiday, so if you choose to teach in China I assume you would take the time to familiarise yourself with local holidays/customs etc, therefore this is standard.

You'll see from my post that i agree it's standard - in fact the first two words of my post state that this is "standard procedure". I'd also agree that people coming to work in a foreign country should find out as much as possible about that country and it's working conditions prior to arrival. That being said, there is always going to be things that you haven't considered and these forums are used by many to help fill the gaps.
Whereas it is standard procedure in China to make students study and teachers work during the weekend to compensate for a public holiday that falls during the week it is not standard procedure in the majority of countries that foreign teachers hail from. Therefore, confusion is an understandable problem. In fact the initial e-mail from Marcus's employer isn't very clear. They are hedging their bets on what the school he works at will decide to do "Different schools may adjust their own schedule time" and "if you get work during the Tomb-Sweeping Festival" are rather vague statements. In the city i work i can tell you that the vast majority of schools and unis will follow the official days off as 2nd-4th April but there are a few exceptions (including the top primary school in the city) who will go with Sat, Sun & Mon as days off. It's worth teachers considering this even if only to prompt them to ask what's going on with working days over the next couple of weeks. It'll also be worth them considering what will happen with 1st May holiday and 23rd June (Dragon Boat Festival).

I fail to see how this is not 'conducive' to a good teaching environment?

Let me spell it out very clearly. Let's say for example that you work at a training school and your normal days off are Weds & Thurs that means that with the move of your regular days off you may well find that you work an extended period without break.

31st Sat - Day Off (moved from Weds)
1st Sun - Day Off (moved from Thurs)
2nd Mon - Given as the public holiday
3rd Tues - work
4th Weds - work (this was your day off but now moved to sat and there's a good chance that you'll teach your classes from the 31st here)
5th Thurs work (this was your day off but now moved to sun and there's a good chance that you'll teach your classes from the 1st here)
6th Fri - work
7th Sat - work
8th Sun - work
9th Mon - work
10th Tues - work
11th Wed - work
12th Thurs - back to regular day off

That's 9 days straight without a break. Teachers are likely to be quite tired by the time they get towards the end of that stint so yes i fully believe that their lessons will suffer as a result. Do you disagree with this point? Are teaching standards better when a teacher is rested and working within their standard routine or when they are tired?