Punctuate This

Recently I gave my students a writing test. On it I wrote various punctuation symbols and told the students to write the names of the symbols in the space provided. Punctuation seems to be VERY difficult for my students and frequently even my more advanced students forget to use a period When I got the tests back I found some peculiar answers. Next to the apostrophe symbol some of my students wrote: aperstropy, epertropi and brain. Next to the period symbol some of my students wrote, perpheous, peirince and divination. The funny thing is that I wrote all the answers on the board right before I gave them the test.