第二十二课

 22 balance天平

Questions and speculation问题与猜测

What is the quality of an egg? 一枚鸡蛋的质量是多少?

I estimate that …我估计.....

Use a measuring tool to weigh it. 用测量工具称一称。

Exploration and Practice探究与实践

Know the balance. 认识天平。

hand指针

dividing plate分度盘

weight法码

pallet托盘

Balanced nut平衡螺母

rider bar 游码标尺

Scales are tools used to measure the quality of objects. Commonused units of quality include grams, kg, tons, etc. The mass of the object measured by the balance is generally gram as a unit by the symbol " g". 天平是用来测量物体质量的工具。质量的常用单位有克、千克、吨等。天平所测物体的质量一般用克作单位，用符号“g"表示。

●How to use the balance to accurately measure the mass of the object? 怎样使用天平准确测量物体的质量?

Method guidance方法指导

1.Place the balance horizontally. Travel code returns to zero. Adjust the balance nut so that the pointer is in the center of the dial水平放置天平。游码归零。调节平衡螺母，使指针指在分度盘中央。

2.Put the left plate to weigh the items, the right plate to put the weight. The weight is clamped with tweezers, first large after small. dial the swim code again and point the pointer to the center of the dial again. 左盘放要称量的物品，右盘放砝码。砝码用镊子夹取，夹取时先大后小。再拨动游码，使指针再次指向分度盘中央。

3.Read the weight quality, then read the scale of the swim code, the two is the quality of the object. 先读取砝码质量，再读取游码的刻度值，两者相加就是物体的质量。

Estimation of mass ratio with balance用天平测量物体的质量比估计.....

Expansion and Innovation拓展与创新

Understand more tools for weighing the object mass. 认识更多的称量物体质量的工具。