Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 620 · 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.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) dry juice is see-through (c) it turned into air (d) the paper ate it
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we measure it (c) we keep it the same
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a mirror (d) lemon juice
4. 4.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) a cotton bud (d) a battery cell
5. 5.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) a battery cell (d) white paper
7. 7.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) yeast (c) turmeric powder (d) a balloon
8. 8.True or false: cutting the lemon is a job for an adult. (a) False (b) True
9. 9.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
10. 10.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) turmeric powder (c) white paper (d) a magnet
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we keep it the same (c) we measure it
12. 12.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) it gets darker (d) writing stays faint
13. 13.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) the juice scorches first (d) heat adds colour
14. 14.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
15. 15.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) yes, if cooled (d) no, it stays brown
16. 16.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) whoever is fastest (d) only an adult
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) how dark the writing is (c) the ironing time (d) the kind of juice
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we keep it the same (c) we change it
19. 19.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
20. 20.🔍 Which is the odd one out? (a) ironing the paper (b) reading the message (c) dipping the cotton bud (d) letting the paper dry
21. 21.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a mirror (c) lemon juice (d) a cotton bud
22. 22.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) yeast (c) turmeric powder (d) an adult with an iron
23. 23.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
24. 24.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
25. 25.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
26. 26.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) plugging in the iron (d) letting the paper dry
27. 27.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
28. 28.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) dipping the cotton bud (c) reading the message (d) letting the paper dry
29. 29.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) a cotton bud (c) a small bowl (d) white paper
31. 31.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
32. 32.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) yeast (d) an adult with an iron
33. 33.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
34. 34.True or false: ironing the paper is a job for an adult. (a) False (b) True
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the ironing time (c) how dark the writing is
36. 36.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
37. 37.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) writing the message (d) plugging in the iron
38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) lemon juice (d) turmeric powder
39. 39.True or false: reading the message is a job for an adult. (a) True (b) False
40. 40.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a magnet (c) turmeric powder (d) a cotton bud

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