Input/output tables are a great way to teach students about operations like addition and subtraction. These tables help to highlight the connection between input values and output values, making it easier for students to grasp these mathematical concepts. In this article, we’ll discuss several activities that teachers can use to help students learn how to use input/output tables for addition and subtraction by 100.

**Activity 1: Fill in the blanks**

In this activity, students are given a partially completed input/output table, with some of the input or output values missing. Students must fill in the missing values using their knowledge of addition and subtraction by 100.

For example, a teacher might provide a table like the following:

Input | Output

——|——-

200 | ?

300 | 500

? | 700

600 | 800

Students would need to use mental math to figure out the missing input or output values. They might notice, for example, that adding 100 to 200 gives an output of 300, so the first missing value is 300. They might similarly recognize that subtracting 100 from 800 gives an input value of 700, and fill that in as well.

**Activity 2: Add and Subtract by 100**

In this activity, students are presented with a set of numbers and must add or subtract 100 to each number to create a new set of numbers. The input/output relationship can then be used to create an input/output table.

For example, a teacher might provide a set of numbers like the following:

5, 205, 305, 405, 505

Students would then add 100 to each number to create a new set of numbers:

105, 305, 405, 505, 605

They can then use this input/output set to create an input/output table like the one below:

Input | Output

——|——-

5 | 105

205 | 305

305 | 405

405 | 505

505 | 605

**Activity 3: Number Patterns**

This activity involves finding patterns in numbers, making predictions, and testing those predictions using input/output tables.

For example, a teacher might ask students to look at the following pattern of numbers:

100, 200, 300, 400, 500

Students can identify that each number is 100 more than the previous number. They can then use this pattern to make predictions for future numbers in the pattern. For example, they might predict that the next number in the pattern is 600 because it follows the pattern of adding 100 to the previous number.

Students can then test their prediction by creating an input/output table using the pattern they’ve identified:

Input | Output

——|——-

100 | 200

200 | 300

300 | 400

400 | 500

500 | 600

By using these activities, students can develop a solid understanding of addition and subtraction by 100. These activities can be easily adapted to suit the needs of different learners, making them a great addition to any classroom. With practice, students will be able to use input/output tables to solve increasingly complex problems, building the skills necessary for success in mathematics.