Today is Wednesday,May.5th.2021

Addition and subtraction

It’s a quetzal.

How long is quetzal’s body?

It’s 7 inches long.

How long is quetzal’s tail?

It’s 21 inches long.

What is the length of the quetzal?

7+21=28

To find out the sum of seven and twenty-one, we can use blocks.

There are two tens in tens place and eight ones in ones place.

So seven and twenty one is twenty-eight.

It’s 28 inches long.

Practice:

Key Words

sum, addend, add, regroup rainforest, Quetzal, length

Key Sentences:

21+7=28

1. Twenty-one plus seven equals twenty-eight.

And seven plus twenty-one equals twenty-eight.

2. In the number sentence 21+7=28, 28 is called the sum of 21 and 7.

3. What do we call 21 and 7?

   We call 21 and 7 addends.

 There are two addends in this number sentence.

Learning Objectives:

1. 学生能不进位，求出一个两位数和一个一位数的和，并能用数学术语表达求得的过程；

2. 学生能通过进位得出两个两位数的和，并能用数学术语表达求得的过程；

学生认识到两个加数(addend)的顺序不影响他们相加的和(sum)。

Homework:

1. 读语音链接

2. 反馈单，要求用英文思维体现出计算过程。