standard_description: Solve word problems that call for addition of three whole numbers whose sum is less than or equal to 20, e.g., by using objects, drawings, and equations with a symbol for the unknown number to represent the problem.
problem_activity: Problem 1
a.   Ms. Needham made a lasagna for dinner with her family. She cut the lasagna into 12 pieces. Her family ate 4 pieces of lasagna the night that she made it. The next day, they ate 3 more pieces. What fraction of the lasagna did Ms. Needham’s family eat altogether?
b.   Ms. Roll is stringing beads to make a 16-inch necklace. At the end of the first night of working on it, she has 5 inches of beads strung. At the end of the second night of working on it, she has another 7 inches of beads strung. What fraction of the necklace has Ms. Roll completed?
Problem 2
Solve. Show your work with an area model or a number line.
a.
$$\frac{7}{8}+\frac{6}{8}$$
b.
$$\frac{13}{12}+\frac{5}{12}$$
Problem 3
Solve. Show or explain your work.
a.
$${5{1\over8}+{5\over8}}$$
b.
$${9{11\over12}+{11\over12}}$$
c.
$${3{4\over17}+4{8\over17}}$$
d.
$${2{11\over15}+2{13\over15}}$$


aligns: no