YES we do & we have 620 kids in our K-5. Actually ALL our elementary schools and middle schools have it. We cover insurance for any damage to the school, injuries that may be sustained, liability from any harm to an attendee, etc. We also have riders to the policy for when we have special games and the inflatables.
If the board of ed will not back you if someone gets hurt, your PTO is liable for all bills. Suggest getting a policy to protect your bank account. I don't know why your previous boards didn't want to discuss it--its protection for the organization.

I recently became President of the PTO at my childs elementary school. One of the very first things that was brought to my attention was that the PTO is required to sign a form provided by the district prior to any event the PTO holds. It basically states that the district and its officers, directors, and agents are exempt and protected if there were to be any problems at a PTO event resulting in lawsuits. However, The PTO doers NOT have insurance and apparently the past boards were not willing to discuss this with the principle of the school. Just from being part of other organizations with officers...such as HOA boards....I know we are required to carry officers and directors liability insurance to protect us and our spouse from suit. It is a K-5 with about 750 students. Do you guys carry insurance?