Us girls carried those knives, too, along with our bag of marbles. The knife game was mummily-peg (sp)...a skill of knife flips. Big sin of the age...stepping on the lawn next door as the old lady guarded it with her broom.
My dad told me about 'mumbly-peg' games at recess. It was kind of like playing 'horse' at basketball. They would start with one blade out, throw the knife at a spot on the ground and make it stick. Then they would challenge each other to do it with the blade halfway out, both blades out, etc. Teachers took this in stride. Throw knives for awhile, dodge ball for awhile, maybe a game of tag.
Oh gosh, the NEA might be reading this! Sorry!