找一张超过小娃身高的纸，我找了一张大牛皮纸，让小娃平躺在这张大纸上，用马克笔，绕着小娃的身体一圈，把身体轮廓画下来。
把图画纸挂在墙壁上。占了大半堵墙壁，隔几天画一个人体器官，找一些适合小娃读的比较浅的人体生物的书，网上很多。和小娃一起读，读完让娃在墙壁上画那个人体器官。
象这样，我们这几天在画消化系统。
学完一个人体系统，布置一个作文题，让娃们写一写关于消化系统的小作文，小娃刚刚写
A journey of a donut
Hi. I am a piece of donut. After you chew me in your mouth, I will start a two-day journey through your digestive system.
The digestion starts with your teeth breaking me down into smaller pieces. The saliva in your mouth works to dissolve me easier and faster. Then I travel to your esophagus. It is a narrow tube that connects your throat and your stomach. The stomach is full of a kind of acid known as gastric acid. It kills the bacteria in the donut that you just ate. The stomach acid further dissolves the donut puree and allows it to be absorbed by the small intestine.
Upon entering the small intestine, the donut puree crosses a large number of bumps, known as "villi". Using the villi, the donut puree is pushed through smoothly, and nutritional elements are transported from the donut puree to the blood.
The liver adds bile and the pancreas adds enzymes. Released into your small intestine, they work together in the donut puree to dissolve the fat. Carrying nutrition, the blood flows from the small intestine to your liver, where poison and waste are filtered out. Your whole body receives nutrition from clean blood.
Your body is pretty smart to tell when you need nutrition. "Glucagon" is a hormone made by your pancreas that tells the liver to release more sugar into the blood. On the other hand, if you ate too many donuts, insulin is a hormone produced by your pancreas that instructs your liver to stop releasing sugar into your bloodstream. The sugar will be stored in your liver for future use.
The leftover donut marches to your large intestine and then releases out of your body. Sadly, I have become a waste. My journey is complete.
还可以在吃饭的时候，和娃们一起进行趣味竞猜，比如血从小肠出来流到哪个器官？ 哪个器官可以分泌酶帮助消化等等。胰岛素是做什么用的？
人体生物比化学物理直观，适合小娃先学。小孩子对自己的身体有种天然的好奇心。了解自己的身体是怎么运作的，本身就是一个感兴趣的话题。
人体生物还可以结合健康话题一起来讨论，比如为什么不喝酒，酒精从消化道进入血液，血液流到肝脏，酒精在肝里面分解。产生有毒的乙醛，伤害肝细胞，长期喝酒会造成肝脏中毒而硬化。还有画完肾脏，可以讲一讲肾脏的功能，为什么要保护自己的肾脏，drug 从肾脏filter, 毒品直接损害肾脏细胞， drug overdose 造成kidney failure，是死因的一种。
带娃去超市看一看健康的猪肝脏和猪肾脏，都是新鲜柔软的，喝酒和吸毒就是把健康的肝脏和肾脏泡在有毒物质中，让器官的细胞蛋白质变性，看看肝硬化的照片，对喝酒伤肝会有触目惊心的印象。我觉得引导娃学会珍惜自己的身体是人生最重要的第一课。
