High school moves fast, and the concepts stack up before you have time to absorb them. When a topic from class or a homework problem refuses to click, you do not need a page of search results, you need someone to walk you through *why* the answer is what it is. That is what Lensia does, and it is the best AI for high school students who want to actually understand the work. It is a Chrome extension, and the part you will use most is a sidebar chat that opens next to your page and stays there: you ask a question, read the explanation, ask a follow-up, and keep going until it clicks. When one line on the screen trips you up, a quick screen capture explains it in a couple of seconds. Install Lensia free. Setup takes about 30 seconds.
Lensia is a study aid. Use it to understand concepts, make your own practice problems, and check your work *after* you have tried it yourself. Using it during a graded test where AI is not allowed is cheating, and that is not what this is for. The habit that actually raises your grade is simple: attempt first, then use Lensia to find the gap.
The sidebar chat is where you study
Click the Lensia icon in your Chrome toolbar, click the small Lensia widget in the corner of any page, or use the sidebar shortcut, and a chat opens in Chrome's side panel right next to your work. It is on every plan.
The reason it beats pasting a question into a random tab is that it holds a whole conversation:
- Conversation history stays between sessions, so the notes you worked through last week are still there the night before the test.
- Bookmarks save the explanations you know you will reread.
- A model picker lets you start an easy question on a fast model, then switch to a stronger one when a math proof or a tricky chemistry step needs more care.
Say a paragraph in your biology reading makes no sense. Paste it into the sidebar and ask for it in plain English. Then type "give me two practice questions on this," try them yourself, paste your answers back, and ask where you went wrong. All of that happens next to the reading, which is how it sticks. For a full routine, read the study smarter guide.
Quick answers without leaving the page
Not everything needs a full chat. Sometimes you are reading and one question stops you. Press Ctrl+Shift+X, drag a box around it, and a step-by-step explanation floats up on top of the page in about three seconds. The page stays visible underneath, so you never lose your place.
Two things keep the floating panel useful past that first capture:
- Ask Mode turns the panel into a typing box. Write your own question and attach up to three images from your screen, which is handy for comparing two diagrams or asking something a single screenshot cannot hold.
- Quick Capture (
Ctrl+Shift+F) reuses your last capture box without redrawing it, so a worksheet of similar problems takes one keypress each.Ctrl+Shift+Ehides the panel and brings it back.
Both surfaces run on the same AI. For the full picture of how the two surfaces fit together, read how Lensia works.
What works best by subject
- Multiple choice: attempt it, then ask the sidebar or capture the question to hear why the right choice holds and the others fail.
- True or false: quick and reliable for factual review in history, biology, and vocab.
- Fill in the blank: give the sentence and the context around it, and Lensia explains the term or number and how to reach it.
- Reading comprehension: capture the passage and question together, and it shows how to find the answer in the text.
- Math and science: paste or capture the full problem with its numbers and units. Turn on reasoning mode for multi-step work. For the full math workflow, read AI for math homework.
Which plan does a high schooler need
Every plan signs in with Google, and there is no credit card to start. Sign in once to activate.
| Plan | Usage | What you get |
|---|---|---|
| Free | Starter | Sidebar chat with history and bookmarks, the capture panel with Ask Mode, Quick and Standard models, and the Lensia Max router |
| Basic | About 10x Free | Reasoning toggle, web search, fetch URL, custom instructions, and Advanced models |
| Pro | Highest | Agent mode in the sidebar and Auto-Solve on Vocabulary.com |
Lensia Max is the auto-router: leave the model on it and it picks a fitting Quick or Standard model per question and takes 15 percent off the cost. Reasoning mode is a single on/off toggle, not a slider, that tells the AI to slow down on hard problems. Advanced models like GPT-5.5, Gemini 3.1 Pro, and Claude Opus 4.8 come with Basic and Pro. Custom instructions let you save your grade level, subject, and how you like explanations written, and every answer adjusts to that.
For a side-by-side with other study tools, read the AI study helper guide for students.
Get started today
Lensia is a free Chrome extension that keeps an AI tutor next to whatever you are studying and explains any question on your screen in a few seconds. Install it in about 30 seconds, open the sidebar on the first thing that has you stuck, and use Ctrl+Shift+X on the next problem you want explained fast.
Install Lensia free and use it on your next study session.