The boy was assaulted by a male youth, who punched him to the back of his head at around 8.15am yesterday (Tuesday).
It is believed the suspect was with a group of other male youths, all aged between 15 and 18, at the time of the incident.
The victim was left shaken but uninjured.
If you can assist with the investigation, contact Lincolnshire Police in one of the following ways:
• Call 101 and quote incident reference number 53 of January 14.
• Email [email protected] and quote the incident number.
• Contact Crimestoppers, anonymously, by calling 0800 555111.