心算整十数的加减法
Adding and subtracting tens mentally
能通过心算以及实物、图片等直观方式，完成两位数与整十数的加法和减法。
Add and subtract a two-digit number and tens mentally and using concrete/pictorial representations
学习证据 / Evidence
- 能心算 45 + 30 = 75
- 能心算 82 − 40 = 42
- 能说明在加减整十数时，只有十位上的数字发生变化
- Calculate 45 + 30 = 75 mentally
- Calculate 82 − 40 = 42 mentally
- Explain that only the tens digit changes when adding/subtracting tens
评估问题 / Assessment
{{name}}能快速心算出“54 + 30”或“78 − 20”吗——并知道计算时只有十位上的数字会发生变化？
Can {{name}} quickly work out '54 + 30' or '78 − 20' in their head — knowing that only the tens digit changes?