At the end of 2004 Pennsylvania passed Bill 873 termed the "School Zone Safety Act," which increased the penalties in a school zone. This new PA law increases the maximum traffic fine for speeding in a school zone to $500 and 3 driver license points if the driver exceeds the speed limit by more than 11 mph.
For a second or subsequent offense the law allows for the driver to face a 60 day license suspension. Previous to this new law being enacted, speeding in a school zone had a maximum fine of $35 (plus associated fees) and $2 for every mph over 20 mph.
Other school safety offenses to keep in mind include improperly meeting or overtaking a school bus. For these traffic offenses a driver can be fined $250 for each violation. Additionally, a conviction will result in a 60-day driver's license suspension and assessment of 5 points on the operator's driving record.
If does not appear that your license will be suspended for this offense but points will be assigned to your driving record. The law information above stated 3 but it likely since you were going 21 mph over the 15 mph speed limit it may be 4 points. To find out for certain the penalties you will receive for this speeding violation contact the court listed on the ticket and/or the Pennsylvania Driver and Vehicle Services.