Chapter 3 is the API itself and the largest block in the syllabus: 240 of the 1200 instruction minutes. Driver lifecycle and setup, finding and interacting with elements, waits and synchronisation, navigation and history, windows and tabs, frames, native alerts, dropdowns and Actions. Selenium 4 only — older tutorials teach calls that have changed or gone.
It is also the largest part of our pool for this certification. Questions here describe a symptom and expect the mechanism, not the syntax.
Where candidates lose points:
Mixing implicit and explicit waits. Setting an implicit wait and then using WebDriverWait produces unpredictable timeouts, because both are waiting at once. Pick one strategy per suite — explicit.
Presence, visibility and clickability are three different conditions. An element can be in the DOM and invisible, or visible and covered by an overlay. Match the ExpectedConditions to the symptom described, not to the first one you remember.
The three exceptions that each mean something specific. NoSuchElementException — never found. StaleElementReferenceException — found, then the DOM was replaced, so re-locate rather than retry the click. ElementClickInterceptedException — something is on top of it.
Switching context and forgetting to switch back. Frames, windows and alerts each need an explicit switch; after working inside a frame you must return to the default content before touching anything outside it. This is the classic trap.
Reading the wrong value. For an input field, the text a user typed is in the live value, not in the rendered text — getAttribute("value"), not getText().
Fixed sleeps. A hard sleep is always the wrong answer: too short on a slow day, wasted time on a fast one.
This chapter is covered most heavily (21 questions) in A4Q Selenium Tester — Mock Exam 6 (Waits, Synchronisation & Test Stability)