Divide the words into two groups. The first one is the group with the article "a". The second one is the group with the article "an".

• Группы
  • "a"
  • "an"
• Варианты
  • map
  • blackboard
  • sharpener
  • ruler
  • school bag
  • notebook
  • book
  • eraser
  • exercise book
  • atlas