School districts across the country face budget cuts just about every year.
Teachers often step in to close the gap. In the 2012-2013 school year, public school teachers spent $1.6 billion of their own money on classroom supplies.
CBS News' Adriana Diaz visited Dawes Elementary in Chicago and found fifth graders getting a hands-on lesson in engineering by launching catapults.
Their teacher, Amani Abuhabsah, explains the experiment: "The kids will analyze their data. And they'll redesign their experiment, so that whole cycle of engineer design process is reinforced through this activity."
But the catapults kits weren't purchased by the school system or anyone who lives in Chicago. They were a gift made through the crowdfunding website Donors Choose, an online charity where teachers post classroom materials they need, and anyone can help cover the cost.
Citizen philanthropists have paid for more than 98 percent of Ms. Abuhabsah's projects -- supplies ranging from microscopes to baking soda.
Charles Best started Donors Choose 14 years ago during his first year as a public school teacher in the Bronx.
"My colleagues and I would spend a lot of our own money on copy, paper, and pencils. I just figured there are people out there who would want to help teachers like us, if they could see exactly where their money was going," Best said.
Today, more than half of all public schools in America have at least one teacher who's created a project on Donors Choose. In response, 1.5 million people have given more than $250 million.
"People not only want to support public schools, but people warm to this idea of being a philanthropist, even if they might have only have $5 to spare," said Best.
Google and Staples donated $384,000 this summer to fund every outstanding project in Chicago public schools. Mayor Rahm Emanuel made the announcement at Dawes Elementary.
"It's helpful for specific teachers and specific classrooms with a specific project. And that's a good thing," said Emanuel.
Like many school districts across the country, Chicago schools are working to do more, with less. Last year, officials closed more than 50 schools and announced they would lay off thousands of teachers.
While Emanual does not think Donors Choose is the future of education, he believes "it's a tool in the toolbox."
A tool Best hopes can spur policy change. "We think there's nothing like sunlight to mobilize and energize citizens to demand change of their elected officials."
To do that, Donors Choose is making their internal data public. Now anyone can see what teacher requests come from which schools.
"If we can show the world that there are students in all sorts of communities who don't have the material they need for a great education, that will be the first major step to doing something about it," Best said.
When people fulfill a project, Donors Choose actually buys the supply and ships it to the teacher. And in response, the kids write notes to the donors.