Math Mammoth Grade 4-A Worktext

Math Mammoth Grade 4-A Worktext is the student book for the first half of grade 4, and part of the Math Mammoth Grade 4 complete curriculum. This book covers addition, subtraction, patterns, graphs, large numbers, multi-digit multiplication, time, and measurement.
The worktext contains both the necessary instruction and the problems & exercises (the 'text' & and the 'work'; thus a "worktext"), and is fairly self-teaching.
The curriculum meets and exceeds the Common Core standards. Please note this is a student worktext and does not contain the answers. The answer key book is available separately.
Features
Math Mammoth focuses on conceptual understanding. It explains the "WHY", so your children can understand the math, not just learn "HOW" to do it.
Concepts are often explained with visual models, followed by exercises using those models. These visual models can take the place of manipulatives for many children; however, it is very easy to add corresponding manipulatives to the lessons if so desired.
The curriculum is mastery-oriented. This means it concentrates fairly long on a topic, delving into its various aspects. This promotes conceptual understanding, as opposed to spiral curricula that often tend to jump from topic to topic too much.
There is a strong emphasis on mental math and number sense.
It requires very little teacher preparation.
The curriculum has no separate teacher's manual nor is it scripted. The introduction to each chapter has some notes for the teacher concerning the material in the chapter. All the instruction is written directly to the student in the worktext, and there also exist accompanying videos where you can see Maria herself teach the material.
After each chapter introduction, you will find a list of Internet links and resources (games, quizzes, animations, etc.) that can be used for fun, illustrations, and further practice.