分数乘法
Multiplying fractions
理解 a/b 是 1/b 的倍数；借助直观模型，用整数乘真分数和带分数（例如 3 × 2/5 = 6/5 = 1 1/5）。
Understand a/b as a multiple of 1/b; multiply proper fractions and mixed numbers by whole numbers, supported by visual models (e.g. 3 × 2/5 = 6/5 = 1 1/5)
学习证据 / Evidence
- 用连加或规则 n × a/b = (n×a)/b 计算 4 × 3/8。
- 计算 2 1/3 × 3，并把结果写成带分数。
- 用直观模型说明为什么 5 × 1/4 = 5/4。
- Calculate 4 × 3/8 using repeated addition or the rule n × a/b = (n×a)/b
- Multiply 2 1/3 × 3 and express as a mixed number
- Use a visual model to show why 5 × 1/4 = 5/4
评估问题 / Assessment
如果一份食谱需要用 2/3 杯黄油，而 {{name}} 想把食谱做三份，{{name}} 能算出一共需要多少黄油吗？
If a recipe uses 2/3 of a cup of butter and {{name}} wants to make it three times over, can they work out how much butter they need in total?