Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 1 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a small bowl (c) white paper (d) a mirror
2. 2.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) reading the message (d) putting the iron away
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a small bowl (d) turmeric powder
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) white paper (d) a battery cell
5. 5.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) yes, in the dark (d) no, it stays brown
6. 6.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we keep it the same (c) we change it
8. 8.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) skip washing (c) lick your fingers (d) rub your eyes
9. 9.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
10. 10.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) a small bowl (d) a magnet
12. 12.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we measure it (c) we change it
14. 14.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it is sticky (d) it can burn skin
15. 15.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
16. 16.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the same cotton bud (c) the same paper (d) the kind of juice
18. 18.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
19. 19.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
20. 20.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
23. 23.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
24. 24.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) the paper ate it (c) it turned into air (d) dry juice is see-through
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) lemon juice (c) a balloon (d) a small bowl
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the iron setting
27. 27.🔍 Which is the odd one out? (a) letting the paper dry (b) ironing the paper (c) putting the iron away (d) plugging in the iron
28. 28.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
29. 29.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the iron is brown (c) heat adds colour (d) the juice scorches first
30. 30.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) True (b) False
32. 32.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) brown (c) blue (d) white
33. 33.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
34. 34.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) dipping the cotton bud (d) plugging in the iron
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the kind of juice (c) the ironing time (d) the same paper
36. 36.True or false: putting the iron away is a job a child can do. (a) True (b) False
37. 37.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) musical (c) magnetic (d) chemical
38. 38.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
39. 39.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) putting the iron away (d) writing the message
40. 40.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) turmeric powder (c) an adult with an iron (d) a battery cell

Free science experiments lessons, practice and worksheets at talentjr.in/science-experiments-for-kids