classroom.jpgUnit 9 reviews and builds on children's growing knowledge of story problems. Whereas, previously, children worked with story problems that involved actions, here they solve story problems that involve categories and subcategories of objects--for example, apples and bananas as subcategories of fruit. Children also work to solve story problems that contain extra information, as well as some that require multiple steps to solve.

Math Expressions strikes a balance between promoting children's natural solution methods and introducing effective procedures. Children begin by using their own knowledge to solve problems and then are introduced to research-based accessible methods, which are discussed so that children understand them. In the process, many teachers discover new meanings behind their own solution methods and come to understand the methods that children use.

Problem Solving
Problem solving means engaging in a task for which the solution method is not known in advance. In order to find a solution, children must draw on their knowledge, and through this process, they will often develop new mathematical understandings. Solving problems is not only a goal of learning mathematics but also a major means of doing so. Children should have frequent opportunities to formulate, grapple with, and solve complex problems that require a significant amount of effort, and then be encouraged to reflect on their thinking.

2-Digit Numbers
In Unit 8, children solved problems with 2-digit totals. In this unit, children explore problems with 2-digit unknown partners. These problems extend children's understanding and use of place value concepts. The most common solution methods are to use 10-sticks and circles to count on by tens and ones.
37 + ___ = 61 Example: Children keep 37 in their heads and count on, 38, 39, 40, 50, 60, 61, while drawing a circle for each count of one and a stick for each count of ten. They can use this picture to identify the amount of the missing partner.

Important Words
Since the key to any problem is understanding what is being asked, Unit 9 continues to focus on important terms such as altogether, the rest, some, in all, and total. Children are sometimes asked to retell story problems to show that they understand what is being asked.

Fuson, Karen, Math Expressions, Unit 9 Overview