Why? Because for the first time since the 1990s, school budgets are being cut in real terms. What's more, those cuts are on such a large scale that they can only severely impact children's education.
£3 billion in cuts by 2020 - a figure that cannot be in dispute as it is accepted by both the National Audit Office and the House of Commons Committee of Public Accounts - is a huge cut. As the schoolcuts.org.uk calculations demonstrate, it means that every primary schools stands to lose over £100,000, secondary schools nearly £0.5 million.
Those are averages, but some schools stand to be hit even harder. Which ones? An analysis by the Child Poverty Action Group of the school cuts figures shows that it will be schools with the poorest children that will lose out, those families who can least afford to see their educational opportunities stolen from them.
Schools in the 50 worst hit local authorities stand to lose over £500 per pupil. The worst hit, Southwark, is predicted a cut of 16%, over £1,000 per pupil, equivalent to cutting over 800 teachers from their posts.
These aren't just future predictions, school cuts are already happening. The National Audit Office confirms that 60% of secondary schools were already having to spend more than their annual income back in 2014/15. Some have now already exhausted any reserves they might have had and are already being forced to make significant cuts.
Across London, NUT members are having to take strike action to try and defend their jobs and working conditions and, in doing so, education and children's learning conditions. Those disputes illustrate exactly what these cuts mean in practice.
In Ark Elvin in Brent, 10 job losses are predicted, mainly support staff. In Plumstead Manor in Greenwich, 30 jobs are to be cut, including teachers and learning support assistants. In nearby Corelli College, 17 jobs are at risk. In Forest Hill in Lewisham a cut of over £1 million will see 15 teaching posts cut on top of over 20 support staff. In Hackney, specialist support teachers and SENCOs are at risk in both the Inclusion Team and at Parkwood Primary School.
These schools give a glimpse of what the school cuts figures show will be coming to 99% of schools unless the £3 billion of funding we need is found: curriculum subjects - cut, support for EAL, SEN and the pupils who need it most - cut, time for teachers to mark and prepare lessons - cut,
The cuts will mean stripping everything to the bone, leaving just the minimum staffing required to keep a teacher in front of a class - but with those class sizes growing even larger.
As the Labour Party drew attention to this week, already over half a million primary school pupils are in classes over 30, that's 1 in 8 of our youngsters - and that's only going to get worse if these cuts continue.
These cuts won't just make things even more difficult for children, it will make things even harder for staff. Long hours and excessive workload mean we already have a teacher recruitment and retention crisis, these cuts will make that even worse.
Staffing will be cut overall and the staff that are left will be overworked, unhappy and constantly changing. That's not the stable environment that children need for their education.
All of those facts and examples spell out a grim picture for our children's future. However, I've not spelt them out for you to feel downhearted, but for you to feel angry - and determined to stop them - because, we can, and must, do that.
Parents and staff care deeply about education. That passion for education is driving a growing campaign to stop school cuts. Meetings of hundreds have taken place across London and beyond. Parents, students and staff have been united in bold and lively protests supporting the local disputes I have mentioned. Today, 200 staff and parents marched through the streets of Catford in support of Forest Hill School.
And, of course, now our campaign has a clear focus and a very immediate timescale. On June 8, we will elect a new Government. We need to make sure that it is a Government that will defend education and reverse school cuts.
We will be supporting local activities, including stalls, hustings, question times, rallies and marches to make sure that school cuts becomes one of the central issues in the General Election campaign.
The NUT doesn't support any political party and so we will lobby every candidate on this issue. But what is clear is that the outgoing Government has shown where it stands - and it stands for cuts. It is a Government that promised to protect school funding - but has broken that promise.
It has tried to cover up the losses hitting nearly every school with the deck-chair shuffling of the National Funding Formula. But robbing Peter to pay Paul does not resolve the problem. Unless there is enough funding overall to meet needs, then no funding formula can possibly be 'fair'.
The Tories haven't even been honest enough to confirm the outcome of their Funding Formula consultation before the General Election campaign starts. That means that suspicions will only grow that, if they think they can get away with it, the outcomes could mean even more money being redistributed away from the worst-hit metroplitan areas.
They claim that they can't afford to invest in education - but
what can be more important than investing in our children's future? Why not use the uninvested wealth sitting in the bank accounts across the Square Mile?
Of course, they can find money when it suits their blinkered educational ideology. NUT research shows that the Government squandered £140 million on 62 free schools, UTCs and studio schools that have either closed, partially closed, or never opened.
They also announced in the March Budget that they were able to find an additional £320 million for education - but only to fund a further expansion of free schools and selective grammar schools.
We should be in no doubt that Government support for selection and for education cuts are part of the same austerity agenda. As a civil servant famously said back in the 1980s "There has to be selection because we are beginning to create aspirations which increasingly society cannot match ... We have to select to ration the educational opportunities to meet the job opportunities". In short, they offer a future where only a select few children are worth investing in, the others can be written off.
That's a future that none of us can accept. We have to campaign to win an alternative future, a future where every child really matters - and that means defeating school cuts.
So let's take the passion and determination that I have seen in the streets of Forest Hill this afternoon, at the rallies that are taking place across the country, and let's defeat school cuts!