Why does the department of education advertise on Google?

Flicking through some recent Hansard archives (10th Oct) and came across this curiousity:

“Damian Hinds: To ask the Secretary of State for Education how much (a) his Department and (b) its predecessor spent on search engine biasing with (i) Google and (ii) other search engines in each of the last five years. [10014]

“Tim Loughton: The Department’s expenditure on paid for search engine marketing, through the Central Office of Information, was £511,923 in 2008/09 and £811,132 in 2009/10…

“No money was spent on search engine biasing.”

Why would a government department spend nearly a million pounds in one year on search engine marketing?