In this chapter, students begin by exploring different patterns in addition.  They add by making 5s and 10s and study patterns in the addition table.

Students move on to use number bonds to practice mental math strategies for 2-digit numbers. Students will use comprehension to add tens or 100 and subtract the extra ones.  While specific strategies are taught, students are encouraged to practice breaking apart numbers and finding what works for them to add mentally. 

Students will go on to learn to add two 4-digit numbers to 10,000 with or without regrouping using base-ten blocks and a place-value chart.  Students are introduced to greater numbers with 4 digits.  These numbers have a thousands place.  Students will realize that the same strategies of adding right-to-left apply, and that regrouping of hundreds is the same as regrouping of tens in that while 10 tens = 1 hundred, 10 hundreds = 1 thousand.  Vertical form is used to find the sum of 4-digit numbers and students are encouraged to check the reasonableness of their answers by rounding.