# What’s the Rule - Part 2 - Lesson for Grade 1, Chapter - Thinking Deeper about Addition and Subtraction—The Unknown Number

In the lesson "What's the Rule - Part 2," specially designed for 1st-grade students, we delve deeper into the concepts of addition and subtraction by focusing on identifying the unknown number. This lesson is a crucial part of the unit "Applications in Operations Within 100," which aims to fortify students' understanding and skills in basic arithmetic operations. Through engaging activities such as "What's the Rule Worksheet," "Missing Numbers Worksheet," "Function Machines: Missing Number," "Guess the Number Worksheet," and both "What's the Rule" and "What's the Missing Number" exercises, students will learn how to determine the unknown value in an equation or number sequence.

Understanding the concept of the unknown number and learning how to find it is essential for students because it lays the foundation for solving more complex mathematical problems in the future. This skill boosts logical thinking and problem-solving abilities, encouraging students to think deeper and apply their knowledge of addition and subtraction in various contexts. By mastering these concepts, students not only enhance their arithmetic skills but also develop confidence in their ability to tackle math challenges, fostering a positive attitude toward learning mathematics.

Estimated classroom time: 17 min
Unit: Applications in Operations Within 100
Click on any activity below to start learning.
1st
3:00 min
What's the Rule Worksheet
worksheet
2nd
3:00 min
Missing Numbers Worksheet
worksheet
3rd
4:00 min
Function Machines: Missing Number
video
4th
3:00 min
Guess the Number Worksheet
worksheet
5th
4:00 min
What's the Rule and What's the Missing Number
Quiz
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• ### Activity 1 / What's the Rule Worksheet

Colorful robots are here to help your child find the relationships between each set of numbers! This adorably illustrated worksheet uses vivid pictures that each contain a rule. Look carefully at each function machine and determine the pattern or relationship found between each pair of numbers in the input and output columns. Then, complete the sheet by circling the robot that contains the correct answer!

• ### Activity 2 / Missing Numbers Worksheet

Solving for missing numbers is a critical pre-algebra skill that even elementary students can learn! All our adorable robots to guide your child along the way while completing this! On either side of each function machine is a robot with a number on his belly, and a missing answer in his hands. Simply look at the other numbers in each graph to find rule and use it to solve for the missing number! Don’t forget to encourage kids to check their answers their work, applying the missing number to ensure it is correct!

• ### Activity 4 / Guess the Number Worksheet

Analyzing relationships between numbers and identifying patterns in math is essential for students to gain a solid number sense! This delightful printable worksheet uses adorable robot illustrations to motivate kids as they find the rule or pattern contained within each function machine on the page. While working, kids will look at the function machine and determine the rule, using that number to solve for the missing number in each graph.

• ### Activity 5 / What's the Rule and What's the Missing Number - Quiz

Students will develop their algebraic thinking skills by generalizing rules for addition/subtraction number problems. In this assessment, students find rules and missing numbers in function machines.