GAZA CITY, Gaza Strip — When Mazen al-Dalo took two of his young sons to see the Palestinian protests against Israel’s decade-old blockade of Gaza, he knew it could be dangerous. Rock-throwing demonstrators were being shot by Israeli soldiers, and armored Israeli jeeps were firing endless volleys of tear gas into the crowds. But it was important to teach the boys about Palestinian history, he said, and give them a glimpse of the modern-day struggles their people face.