Thousands of anxious police patrolled dressed in riot gear...with many shops sealed shut...as an estimated 150,000 students returned to Santiago's streets...demanding educational reforms...especially free education.
In 2 years...students have protested...over 40 times...and often violently...about education's high costs there...and low quality.
Police have grown used to repelling small bands of violent students with tear gas, water cannons, rubber bullets and arrests.
8 police were reported injured...and 109 detained after Thursday's march.
Despite the many protests...conservative billionaire President Pinera has only reduced some financing costs.
Former President Michelle Bachelet...who recently announced a run for the November election...has promised to submit legislation to remove or limit profit motives from education...if she wins the presidency again.