Suppose I am trying to teach a class of 12 children how to build campfires. I would like each pupil to have a flint and steel for the lesson. As it turns out ferrocerium rods can be acquired cheaply for about a dollar each if I bulk-buy them. That leaves loads of leeway for rods getting lost. The problem is no striker is provided.

Is there any common household item I can have the children bring in to use as a striker? My first idea was a butter knife, but after trying this to no avail I realised the knife reads STAINLESS STEEL on the side. I am aware that a carbon-steel knife works as a striker; indeed some paring knives work. But I cannot get such a knife for less than 5 dollars, and I need a dozen plus spares. Moreover if I instruct the children to bring in a knife each, then chances are half will be stainless steel anyway.

Any suggestions?