TalentJR apps
You need: lemon juice in a small bowl, a cotton bud, white paper, and an adult with a warm iron. What happens: the dried lemon writing is invisible; when the adult irons the paper, the words appear in brown. Why: lemon juice has sugars and acid that scorch (turn brown) at a lower heat than plain paper. The browning makes new substances, so it is a chemical change and cannot be undone. Plain water leaves almost nothing.
✓ You passed this lesson’s test.
Heat shows the secret — “dried lemon juice browns with gentle heat before the paper does”
Use it for: Science lessons on chemical changes; a fun spy-style experiment for kids at home with an adult.
Check: Only an adult uses the iron — children dip, write and read ✓
▶ Watch it animatedWork it out in your head or on paper, type the answer and press Check. Stuck? Press “Show me how”.
Right: 0 · Tried: 0
20 questions. Check each answer, then go to the next one. Get 16 or more right to pass.
🏅 Sign in with Google to earn the 🍋 Secret Ink Writer badge when you pass — and a certificate when you finish all 10 lessons of Part 2 · Kitchen chemistry and life. You can still take the test without signing in.
Why does it work? When should you use it? Ask in English, मराठी or हिंदी.
Sign in with Google to ask Free — 20 questions a day.
Prefer a real teacher? TalentJR teachers take live online classes anywhere in India and visit homes in selected cities. Tell us what you need and our team will call you with timings and fees.