Rhyming text and illustrations follow the activities of a group of twelve monsters that diminishes one by one. Includes a section of counting activities.

• 本书文字部分词语押韵，插图俏皮可爱。书中的十二个小怪物会随着故事的发展一个接一个地减少。其中还有一个部分需要小读者们参与进来，进行计算。