when did a dotted quarter note become so hard?

I have been teaching band now for about 27 weeks (give or take a week).  It has been one of the most challenging things I have ever done!  It is hard to get the information from my head to the student's head! Last week we were working with staccato notes.  the concept of short is unfamiliar!  i clapped, sang, had them clap, and nothing seemed to make sense to them... finally i had to make the section a quiz grade for them to actually practice.  Today was the dotted quarter note.  For those of you who are not musically taught it is worth one and a half beats.  So i taught the definition.  i sang the song (Vivaldi's Anvil Chorus). i than had them clap while i struck sticks together.  Finally i brought out the bass drum.  with all my might i struck the head of the drum as they played.  we worked over and over and over again until finally it was somewhat in rythm.  With all the popular music in the world today, i would think that the concept of the dotted quarter would be simple.  every song that has any kind of beat ususes the dotted quarter!  it is a symbol of rythm... which makes me think... is the dotted quarter the problem or is it true that certain kinds of people just have no rhythm?  does heritage actually affect the amount of rythym you have?  does your grand daddy's soul effect the way you tap your feet?  as i look through my elementary class and i imagine their parents the correct answer may be yes!  their heritage may prevent them from ever conquoring the ... dotted quarter!