Unit 2

Place Value and Problem Solving using Addition and Subtraction with Units of Measure


Grade 3




Description: In Unit 2, students use place value understanding to round whole numbers. Students will add and subtract using strategies and algorithms. Students will solve one- and two-step word problems involving addition and subtraction, units of measure and telling time. Students will continue to practice fluency of basic facts involving factors of 2, 3, 4, 5, and 10 and their related division facts.


Louisiana Student Standards for Mathematics (LSSM)

Instructional Outcomes


Additional Cluster Standards

Use place value understanding and properties of operations to perform multi-digit arithmetic.



Use place value understanding to round whole numbers to the nearest 10 or 100.



Fluently add and subtract within 1000 using strategies and algorithms based on place value, properties of operations, and/or the relationship between addition and subtraction.


Major Cluster Standards

Solve problems involving the four operations, and identify and explain patterns in arithmetic.



Identify arithmetic patterns (including patterns in the addition table or multiplication table), and explain them using properties of operations.


Solve problems involving measurement and estimation of intervals of time, liquid volumes, and masses of objects.



Understand time to the nearest minute.

a. Tell and write time to the nearest minute and measure time intervals in minutes, within 60 minutes, on an analog and digital clock.

b. Calculate elapsed time greater than 60 minutes to the nearest quarter and half hour on a number line diagram.

c. Solve word problems involving addition and subtraction of time intervals in minutes, e.g., by representing the problem on a number line diagram.




Measure and estimate liquid volumes and masses of objects using standard units of grams (g), kilograms (kg), and liters (l). Add, subtract, multiply, or divide to solve one-step word problems involving masses or volumes that are given in the same units, e.g., by using drawings (such as a beaker with a measurement scale) to represent the problem.



Enduring Understandings:

Essential Questions:


         Estimation helps us see whether or not our answers are reasonable.

         Using rounding is an appropriate estimation strategy for solving problems and estimating.


         Addition and subtraction are inverse operations.

         Addition means the joining of two or more sets that may or may not be the same size. The counting up strategy can be used to make change.

         Subtraction denotes finding the difference between sets or comparing sets.


         The duration of an event is called elapsed time and it can be measured.

         Mass and volume are important parts of everyday life and can determined a variety of ways.



         Does rounding a number change its value relative to other numbers?

         How are addition and subtraction alike and how are they different?

         How can I show what I know about addition and subtraction, problem solving, and estimation?

         How can I use what I know about addition and subtraction to help me solve problems?

         How can I use what I understand about money to solve word problems?

         How do we round numbers to the nearest ten or hundred?

         How is rounding used in everyday life?

         What strategies can I use to help me tell and write time to the nearest minute and measure time intervals in minutes?

         Why is measurement important in my everyday life?