One of the hot-button areas for all the Democratic presidential candidates is education. How do they propose to make it more affordable and equitable? How do they propose doing that without lowering standards? Most importantly, how do they propose paying for these costly improvements?

Here are the plans of the leading candidates for the nomination — Elizabeth Warren, Joe Biden and Bernie Sanders — on two of the most important education areas: 1) funding to reduce segregation in classrooms and the current, inequitable distribution of education funds and 2) financial assistance for college tuition and the forgiveness of student debt.

First: A Disclaimer

Before getting into the candidates’ plans, let’s remind ourselves that when presidential candidates propose new laws and changes in federal programs to appeal to voters, there’s almost zero chance of these proposals being carried out without modification in the real world. These proposals are aspirational and their most important function from a candidate’s view is to get your vote.

Even when a candidate is entirely sincere in making these proposals, presidents do not make law; that’s Congress’ job and the president can only approve or veto what Congress is willing to send up for signature. For there to be any chance of these proposals being carried into law, Democrats would not only have to win the presidency, they’d also need to control both houses of Congress. Moreover, at least one of these issues may not be subject to federal oversight.

Nonetheless, understanding where each of the candidates stands on these issues is important because it likely indicates how energetically each candidate will work to get their education agenda before Congress and then into law.

Segregated Classrooms and the Inequitable Distribution of Education Funds

Of the three leading candidates, Elizabeth Warren’s plan for reducing segregation in classrooms is the most ambitious and detailed. It’s also the most expensive and would entail a 400% increase in federal funding for schools with primarily low-income students.

Since students in such schools are primarily brown and black, Warren’s plan actually addresses both the segregation problem and the current disparity in the allocation of funds that gives primarily white students a better-funded K-12 education.

Bernie Sanders’ education proposals in these two areas are similar to Warren’s, although, overall, somewhat less costly and less detailed. Sanders specifically addresses what many educators feel is the K-12 elephant in the room: the fact that K-12 education is funded to a significant degree by school district property taxes. Until that changes, there is little hope that brown and black students will get anything like the public school education available to white students.

While Sanders is quite clear that this is wrong and needs to be changed, he doesn’t give a detailed explanation of how that change would come about, what it would cost or how it would be funded. Moreover, the federal government can’t dictate how a state spends its tax revenue and states with conservative governments would almost certainly oppose a federal attempt to reallocate state revenue in the way that Sanders has proposed.

In the 1970s, Joe Biden, although a policy liberal in most respects, opposed busing to reduce segregation in classrooms, and even considered a constitutional amendment to make busing illegal.

For this reason, many progressive educators today still distrust Biden, even though his recent policy statements, like Warren’s and Sanders’, call for substantial increases in federal funding, much of it specifically aimed at improving the educational experience of low-income and therefore largely black and brown students. Biden’s proposals could triple the federal government’s education budget. Warren’s would more than quadruple it.

College Tuition and Student Debt

Warren’s proposals regarding these two closely related issues are unequivocal: she’s proposed free college tuition for all and the cancellation of nearly all existing student debt. Sanders has proposed a similar plan, but has tried to distinguish his plan from Warren’s by stressing that his education proposals would eliminate all student debt.

In reality, there’s not that much difference in the two plans. Warren’s would cover more than three-quarters of all student debt and all debt for families annually earning $100,000 or less. At that point, a sliding scale would decrease the percentage of debt forgiven until students from families with $250,000 annual income or more would receive no federal debt relief. Only 5% of the U.S. population earns that much.

Biden’s proposal for student debt repayment differs from both Warren’s and Sanders’ and calls for the forgiveness of all debt only for families with annual incomes of $25,000 or less. There is less to this plan than meets the eye. The reality is that relatively few children from very low-income families qualify for admission to four-year colleges and many of those that attend two-year community colleges drop out.

Biden has proposed that each year students would repay only 5% of their discretionary income over $25,000. The effect of this on individual families would vary somewhat unpredictably. For many, this plan could eventually require the repayment of all student debt.

How Would These Plans Be Funded?

Unless the federal government were willing to further increase deficit spending, the proposals of all three candidates would require dramatic increases in revenue. Warren’s proposals are the most costly; to pay for them, she has proposed a wealth tax that would hit the billionaire class particularly hard and that has been strenuously and predictably denounced by individual billionaires in government and on Wall Street.

Even philanthropist Bill Gates has expressed some misgivings. Biden’s proposals are the least costly and, in some ways, therefore more likely to be carried into law. But the very fact that two of the three leading Democratic candidates have dared to make these very costly and fairly radical proposals is interesting and reflects a changing American outlook on wealth.

It turns out that nearly two-thirds of Americans favor some version of a tax on wealth, as well as substantial increased taxes on income earned by the wealthiest Americans. Nevertheless, the fact that 1% of the U.S. population controls 40% of the wealth of the wealthiest country in the world suggests that opposition to all these plans will be vigorous and very well-funded.