Secret Course 10
From the Super Mario Wiki
The course starts with the first Bonus Medal immediately in plain sight. Right after this is the first Cannon, which can be used to obtain the second Bonus Medal. After that is the third Bonus Medal before the second Cannon, which can be used to obtain the fourth Bonus Medal. After that is an upside down Cannon and the fifth and final Bonus Medal before the Goal Pole, which can be obtained by jumping on the upside down Cannon's Cannonballs.