正数和负数

理解正数和负数是用来描述具有相反方向或相反意义的量；能在温度、建筑物楼层和银行余额等情境中使用它们。

Understand positive and negative numbers as describing quantities with opposite directions or values; use them in context such as temperature, floors in a building, and bank balances

学习证据 / Evidence

• 在数轴上表示正数和负数，并解释零在不同情境中的含义
• 利用数轴推理，将任意整数加上一个正数或负数
• 从任意整数中减去一个正数或负数，理解减去一个负数相当于做加法

• Represent positive and negative numbers on a number line and explain what zero means in context
• Add a positive or negative number to any integer using number line reasoning
• Subtract a positive or negative number from any integer, understanding that subtracting a negative is equivalent to adding

评估问题 / Assessment

如果{{name}}在天气预报中看到像−3°C和+5°C这样的温度，能不能算出一个日子比另一个日子暖和多少——即使答案要越过零度？

If {{name}} sees temperatures like −3°C and +5°C on a weather forecast, can they figure out how much warmer one day is than the other — even when the answer crosses zero?