Let's modify your question slightly, so that we address the situation in which children not only lack access to education, but to the bare minimum standards of what most of us in privileged communities would consider a dignified life. We should do this because it better delves the true importance of Singer's work and more thoroughly exposes the ramifications of our behaviour. With this in mind:
Suppose that you have enough money to adequately feed, shelter and provide medical care for your child. Are you acting immorally by making such provision while many, many children elsewhere in the world have no access to a safe minimum of water, food, shelter and medical care?
We gain insight into this 'dilemma' by recognising that much of Singer's morality rests, at its foundation, on the concept of fairness.
When we examine questions such as this one through the lens of fairness, it can (should?) prove illuminating and troubling.
Why? Because most of us, if asked, would agree that fairness is a virtue. Many would go further and claim that it is a duty to pursue fairness where possible. We expect or at the very least desire to live in a fair and just world. For some, this fairness is represented by some imaginary equality of outcome. For others it is merely equality of opportunity. Regardless, relatively few people, would argue - if confronted - that children deprived of adequate sustenance, shelter and medical care are being provided either equality of outcome or opportunity. Life for such unfortunates is clearly not 'fair' in the sense most of us typically use the word.
This is a stark disparity; a disparity that we ignore or fail to adequately address despite our own relative wealth.
Singer employs the analogy of a child drowning in a puddle and asks why - if we would be willing to ruin a pair of fine shoes by wading into the puddle to save the child - we are more often than not unmotivated to spend the same money as we would replacing the ruined pair of shoes on a charity providing for children who suffer in circumstances we, by sheer good fortune, have been spared.
It is a powerful analogy, but even without Singer's reminder, it is one many of us already subconsciously intuit or consciously consider and ignore. Many of us using this site likely have what we call 'disposable' income; that is, we not only have an income which satisfies not only our immediate and future needs (in the form of superannuation perhaps, or retirement savings), but enough cash to buy take-away coffee instead of making our own. Enough cash, perhaps, to buy alcohol and cigarettes, to visit cinemas, go on holiday, improve our homes. Some of us have a holiday home and/or investment properties. Many of us buy unnecessarily fine/expensive clothes and food, unnecessary quantities of clothing and food. Some of us even gamble money at odds which we know ensure we will in the long run be certain to lose. (I do not diminish addiction to substances/gaming here. I'm referring to those who are not medically compelled to indulge).
It seems that regardless of what philosophical manoeuvres we are capable of making, it is difficult to deny that for those of us who subscribe to an ideal of fairness:
Given there are reputable, proven, independently-rated charities via which we can demonstrably provide for the wellbeing of people who are truly destitute,
Given that we have the means to donate to such charities far more than we already do,
Are contributing - via neglect - to the ongoing, preventable death, disease and sadness of many people we have the capacity to help in transformative ways.
In doing so, we are failing to pursue an ideal of fairness intrinsic to what our own moral code or compass.
So, "Are you acting immorally by making such provision while many, many children elsewhere in the world have no access to a safe minimum of water, food, shelter and medical care (and education)?".
Few would argue that a person is immoral in providing for their own. It is when we have the means to provide for our own and for others yet fail do do so that we should recognise in ourselves an internal inconsistency which might reasonably be deemed 'immorality'. It would be interesting to know how many of us in such a situation might confess to such immorality. We have enormous self-interest in viewing ourselves as good people who do the right thing by others, for only then can we reasonably expect similar courtesy in return.
Note: There are statistics available for the donation rates of many countries, but it is harder to find material which compares the rate of donation vs 'disposable income'. Many may in fact donate (Eg: 56% of US citizens donated to charity in 2021, at a rate of $574 per person), but it seems fair to assume that given clear enormous annual expenditure on 'luxury products', what people give is a tiny fraction - on average - of what they could afford to give.