In this unit, students will use addition and subtraction to solve elapsed time, liquid measurement (l), and mass (g and kg) measurement problems. Students will build on their understanding of telling time to specifically tell time to the nearest minute and develop strategies and representations to solve elapsed time problems. Students will also develop the concepts of liter, gram, and kilogram by using representations and drawings to solve onestep measurement problems with addition and subtraction.
Key Concepts:
 We can use representations such as a number line to solve situational problems involving addition and subtraction of time (in minutes).
 Representations and drawings can be used to solve onestep situational problems involving addition and subtraction of liquid volumes.
 Representations and drawings can be used to solve onestep situational problems involving addition and subtraction of mass.
Prior Knowledge Needed:
 Fluency in addition and subtraction; (Grade 2, Unit 15; 2.OA.1, 2.OA.2, 2.NBT.5)
 Tell time to the nearest five minutes and represent time on a number line; (Grade 2, Unit 4; 2.MD.7, 2.NBT.2)
Units on the Horizon:
 Using multiplication and division to solve measurement problems (Grade 3, Unit 14)
 Introducing measurement conversions (Grade 4, Unit 6)
 Solving measurement problems using the four operations (Grade 4, Unit 8)
Lessons

Lesson objective: Extend understanding about telling time to telling time to the nearest minute. Students bring prior knowledge of telling time to the nearest five minutes from Grade 2, Unit 4, 2.MD.C.7. This prior knowledge is extended to telling time ...

Lesson objective: Understand that number lines can represent the process for solving addition and subtraction elapsed time problems. Students bring prior knowledge of telling time to the nearest five minutes and representing time on a number line; (Grad...

Lesson objective: Add and subtract to solve elapsed time problems using a number line to show mathematical reasoning. This lesson helps to build procedural skill with solving for the unknown in time problems. A number line is used here because it is a u...

Lesson objective: Solve elapsed time problems where the starting time is unknown by using a number line to represent subtraction. This lesson provides an opportunity for students to apply their knowledge and understanding of telling time and number oper...

Lesson objective: Understand that milliliters and liters are used to measure liquid volumes. Students bring prior knowledge of measuring with inches and feet from Grade 2 Unit 2, 2.MD.A.1, and Grade 2 Unit 3, 2.NBT.B.7. This prior knowledge is extended ...

Lesson objective: Add and subtract to solve liquid volume problems. This lesson helps to build procedural skills with reading and labeling milliliters on a liter graduated cylinder. A vertical number line is used here because it supports reading a scale...

Lesson objective: Solve problems using a number line to show addition and subtraction methods for solving one step liquid volume problems. This lesson provides an opportunity for students to apply their knowledge and understanding of adding and subtract...

Lesson objective: Extend understanding that representations and drawings can be used to solve onestep situational problems involving addition and subtraction of grams and kilograms. Students bring prior knowledge of using a number line to show methods ...

Lesson objective: Add and subtract to solve problems with grams and kilograms using the number line to show the problem solving strategy. This lesson helps to build procedural skills with whole number addition and subtraction using multiple strategies. ...

Lesson objective: Solve problems using the number line to show addition and subtraction strategies. This lesson provides an opportunity for students to apply their knowledge and understanding of addition and subtraction to a reallife situation. Student...