to SpottyCircle
   ca
   cro 7000         ;; replace 7000 with a SLIDER named howManyTurtles
   
   ask-concurrent turtles
   [
     fd random 20
   ]  
end

to SpottyCircle2
   ca
   cro 360              ;; replace 360 with howManyTurtles Slider
   
   ask-concurrent turtles
   [
     ;; if withPen [ pd ]           ;; withPen is a SWITCH control
     
     fd random 10 * 2
   ]  
end