Skip to main content
CBT exams on Lena have specific rules and security measures to ensure a fair testing environment. These rules apply to all CBT exams unless your teacher or school has configured them differently.

Fullscreen mode

When you start a CBT exam, the browser enters fullscreen mode. This removes distractions and ensures you’re focused on the exam.
  • The exam interface fills your entire screen
  • Browser toolbars, tabs, and other elements are hidden
  • If you exit fullscreen, your exam is automatically submitted
Exiting fullscreen will automatically submit your exam. Stay in fullscreen mode for the entire duration of the exam.

Tab-switch policy

The CBT system monitors whether you navigate away from the exam. This includes:
  • Switching to another browser tab
  • Opening a new browser window
  • Clicking on the taskbar or dock
  • Using Alt+Tab or Cmd+Tab to switch applications
  • Minimizing the browser

How it works

  1. Each time you switch away from the exam, a counter increments
  2. When you return, you see a warning message showing how many switches you’ve used
  3. If you reach the tab-switch limit set by your teacher, the exam is automatically submitted

Tab-switch limits

The limit varies by exam (set by your teacher):
Limit settingWhat it means
0 switchesNo tab switching allowed — any switch triggers auto-submission
3 switchesYou get 3 chances before auto-submission (recommended setting)
5 switchesMore lenient — 5 switches before auto-submission
UnlimitedNo restriction on tab switching
Even accidental tab switches count. Before starting your exam, close all other browser tabs and applications to avoid accidental switches.

Auto-submission

Your exam can be automatically submitted (without you clicking Submit) in these situations:
TriggerWhat happens
Time expiresThe duration runs out and the exam is submitted with your current answers
Tab-switch limit exceededYou switch away from the exam too many times
Exiting fullscreenYou exit fullscreen mode (e.g., pressing Escape) — the exam is submitted immediately
Opening developer toolsYou open your browser’s developer tools — a countdown appears, and the exam is submitted if you don’t close them in time
When auto-submission happens:
  • All answers you’ve selected up to that point are saved and submitted
  • Your score is calculated based on the answers you provided
  • The submission is marked as auto-submitted in your results
Auto-submitted exams are final. Your teacher can see whether you submitted manually or were auto-submitted.

Time limits

Every CBT exam has a time limit set by the teacher (e.g., 30, 60, 90, or 120 minutes).

How the timer works

  • The timer starts when you click Begin
  • It counts down continuously — it does not pause if you leave the page or lose internet
  • The remaining time is always visible on screen
  • When time runs out, the exam is auto-submitted

Exam window vs duration

These are two different things:
ConceptMeaning
Exam windowThe time range during which you can start the exam (e.g., 9:00 AM to 12:00 PM)
DurationHow long you have once you begin the exam (e.g., 60 minutes)
You can start the exam at any point during the window, and you’ll get the full duration from that point.

Allowed attempts

Your teacher sets how many times you can take the exam:
SettingMeaning
1 attemptYou can take the exam only once (most common for formal exams)
Multiple attemptsYou can retake the exam up to the allowed number
If multiple attempts are allowed, your best or most recent score is typically used (depends on teacher settings).

Preparing for your exam

Follow these tips to avoid issues during your CBT exam:
1

Close everything else

Close all other browser tabs, applications, and background programs. This prevents accidental tab switches. Your desktop should show only your browser.
2

Use a supported browser

Use the latest version of Chrome, Firefox, or Edge. Safari may have limited fullscreen support. Verify your browser is up to date in its settings.
3

Check your internet

Make sure you have a stable internet connection. If possible, use a wired connection instead of Wi-Fi. Test by loading a web page to confirm connectivity.
4

Disable notifications

Turn off system notifications, pop-ups, and alerts that might pull you away from the exam. Your notification center should be empty or in Do Not Disturb mode.
5

Disable browser extensions

Some extensions can interfere with fullscreen mode or trigger tab-switch detection. Disable them before the exam. You can re-enable them afterward.
6

Plug in your charger

Don’t let your laptop die during the exam. Plug in your charger before starting. Confirm your battery is charging.