... show them this:
http://www.jpost.com/Defense/Article.aspx?id=251346
We are talking about a on-going war fought against terrorists who indiscriminately target civilians and civilian infrastructure with no thought as to who will be killed or injured by their war crimes and who use their own people to shield their activities.
In general, the IDF sums up the past year along the Gaza border as a success. It says 100 Palestinians were killed over the past year in military operations and that nine were civilians.
This is nearly a 1:10 civilian-to-combatant ratio that is unprecedented in any other conflict in the world.
The United Nations, for example, estimates an average three-to-one ratio of civilian-to-combatant deaths in conflicts worldwide. That is three civilians for every combatant killed. Over the past year in Gaza, it has been one civilian for almost every 10 combatants killed.