TOEFL iBT Skills - Synthesizing

The TOEFL iBT presents not only independent skill questions, but also integrated ones. These questions demand synthesizing skills, which involve creating something new by combining two or more sources. What emerges as a result of synthesis is a new perspective, meaning, or idea.

You will need to synthesize on the writing and speaking sections of the TOEFL iBT. For example, on the integrated writing question,  you may be asked to read a short passage, listen to a short lecture and then write your response. This may necessitate comparing, contrasting, and giving your view on a topic. At times you are not asked for your opinion, so make sure you read the directions carefully. Similarly, in the speaking section, you may listen to two parties discussing a topic and then be asked to synthesize and add your opinion. Again, pay close attention to the exact wording of the question and do only what is asked of you.

TOEFL iBT WRITING - SYNTHESIZING RESOURCES
Barron's TOEFL iBT devotes 17 pages to the subject of synthesizing alone. You are given strategies to help you identify themes and connections, to decide which information to select from the two sources and to show you how to follow a plan so you complete the task within the given time limit.

You can learn more about synthesizing by referring to TOEFL writing books and general English writing textbooks and workbooks.