Not sure where you're getting $400/hour since you didn't provide any evidence but the contact is quite clear that the rate is $5000/hour:
> Provide four (4) two-hour sessions at the rate of $5,000.00 per hour for a total of $40,000
> Provide four (4) two-hour sessions at the rate of $5,000.00 per hour for a total of $40,000
https://www.sfchronicle.com/bayarea/article/California-math-...
"The Oxnard district training or others like it don’t include only the time in front of teachers or at the district, but also about 18 hours of preparation, Boaler said, which isn’t specified in the contract. The deal also means significant travel time."
It's not uncommon for consulting to work that way where you pay $X for a report and a couple hours of presentation but theres a bunch of behind the scenes work you're implicitly paying for too.
So her effective rate was probably a little over $1k/hr. Doesn't seem that unreasonable for a Stanford prof.
If you believe that (e.g. if you think the sessions are heavily customized for each school district, and not just the same thing at each place), then you'd divide the 5k by 11+1, getting $417/hour.