The children's teacher at Skinner West Elementary School helped them come up with the experiment, which involved fertilizing a goldfish egg in order to study how the embryo grow in space.
The experiment was aboard the Space Shuttle Atlantis.
At the Field Museum Monday, Skinner students Eric Chen and Eren Fitzgerald examined their goldfish embryo experiment in a test tube. This past weekend NASA returned their experiment to them.
"I've wanted to be an astrophysicist or a scientist or an astronaut for basically all my life, and knowing I could take part in it was amazing," said Fitzgerald.
Chen, Fitzgerald and zoologist and fish expert Mark Westneat checked to see if space had changed the goldfish embryos.
"There were four eggs came back from the space group and one of them appears to have an embryo that is fairly well developed, so that embryo could have still been developing when it went into space, which is very exciting," said Westneat.
There were 77 proposals from students hoping to secure a spot in space for their experiments. Science teacher Kori Milroy, who learned about the Student Spaceflight Experiments Program, was able to land a $20,000 gift from Motorola to secure a spot for the school in space.
The two students sent six goldfish embryos to space to watch them develop. On Monday, they compared them to the six embryos that stayed on earth. Milroy went to Florida with one of the students for the final shuttle liftoff.
"Our students actually became scientists," said Milroy.
The fertilized goldfish eggs did not survive in space. However, now they will be preserved and stay in the museum as part of its permanent collection.
"We would be overjoyed to have the first space eggs in our collection," said Westneat.
"We learned about the growth of the goldfish eggs," said Chen.
"I learned what microgravity can do to little things," said Fitzgerald.