It's being held at the Academy of Natural Sciences of Drexel University on the Ben Franklin Parkway.
4th through 12th graders from all over Philadelphia participate, and it's open to students in public, private, parochial and charter schools. Even home-schooled students can participate.
But what makes this science fair really unique is the fact that it's the oldest urban science fair in the country.
Action News was there as 250 4th through 6th graders submitted their projects Wednesday.
For these younger students the categories included life science, earth and physical science and consumer science.
Sixth grader Jarod Puchino asked whether water can be used as glue - and found out that it can!
The students chose hypotheses ranging from "How does the area of a faucet affect the flow rate?" to "How do you make your sandwich more sustainable?"
The judges say the main thing they look for in the students' answers is procedure.
"We're looking for not so much the results, but the creativity. Did they follow scientific procedures, did they ask questions the right way?" said judge Samir Joshi.
One team of students decided on a subject they called 'Crash Course.'
"My hypothesis," said Webster Elementary School fifth grader LaMeck Beni, "was, if we choose 36 adults to participate in an online texting-while-driving simulation game, we predict a 10 percent decrease in the participation reaction time while texting."
"We wanted to change something in the world that we thought was a big thing in the world," added teammate Jocelyn Miller.
"It was actually confusing to the participants at first, but then they started getting used to it and asked, 'Can we have a second chance?'" said teammate Corey Witcher.
The team's hypothesis was incorrect. The decrease in reaction time for those drivers who texted was much higher than they thought it would be.
"It was actually 21.8 percent and they did really bad," said LaMeck.
The Awards program for the 4th through 6th graders is scheduled for Friday. The winners receive everything from microscopes to college scholarships!
Meantime, the 7th through 12th graders across the city will submit their science projects on March 12th.