Ms Wheeler moved to Manchester to do a physics degree and then a master's degree in virtual environments. She took a well-paid job as a software engineer.
Ms Karim did her physics degree at Bristol before joining the graduate programme for a government agency, then moving into London's Square Mile to work as a business adviser with an international financial services company.
Throughout it all, they remained best friends.
This year, their paths diverged: after studying at the Institute of Education last year, Ms Wheeler, 29, took a job as a physics teacher at St Angela's Ursuline school, back in east London. She lives at home with her parents and earns pound;26,658.
Her friend, 28, as a City business adviser, earns more than twice that, and owns an apartment in Docklands.
"If your motivation is going to be getting a mortgage, getting a house, earning lots of money before you're 30, then don't come teaching," says Ms Wheeler. But she loves her job.
Ms Karim, who works with multibillion-pound companies and international high-fliers, said: "Being in this world opens you up to a lot of possibility."
But at the request of a teacher friend, Ms Karim did agree to serve two years as a school governor. The experience was an eye-opener.
"I believe people's pay should be aligned with how hard they work, and perhaps how much they're contributing socially," she said. "I don't think that is recognised in teachers' pay," she said.