Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 58 · 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.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
2. 2.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) dry juice is see-through (c) it turned into air (d) the ink is magnetic
3. 3.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we measure it (c) we keep it the same
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) how dark the writing is (c) the kind of juice (d) the ironing time
6. 6.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
7. 7.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
8. 8.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) almost nothing (d) blue words
9. 9.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a balloon (c) turmeric powder (d) a cotton bud
10. 10.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) an adult with an iron (c) a cotton bud (d) white paper
12. 12.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
13. 13.True or false: writing the message is a job for an adult. (a) False (b) True
14. 14.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
15. 15.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) writing stays faint (d) it gets darker
16. 16.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) lemon juice (c) a mirror (d) an adult with an iron
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a magnet (c) a small bowl (d) lemon juice
19. 19.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) yeast (c) white paper (d) a cotton bud
20. 20.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) dipping the cotton bud (d) ironing the paper
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we measure it (c) we change it
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we change it (c) we measure it
23. 23.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
24. 24.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
25. 25.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the juice scorches first (c) heat adds colour (d) the iron is brown
26. 26.🔍 Which is the odd one out? (a) ironing the paper (b) dipping the cotton bud (c) cutting the lemon (d) putting the iron away
27. 27.True or false: white paper is needed for the secret lemon message. (a) True (b) False
28. 28.True or false: reading the message is a job a child can do. (a) False (b) True
29. 29.🔍 Which is the odd one out? (a) reading the message (b) plugging in the iron (c) writing the message (d) letting the paper dry
30. 30.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a battery cell (c) a cotton bud (d) an adult with an iron
31. 31.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
32. 32.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
33. 33.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) yes, if cooled (d) no, it stays brown
34. 34.True or false: yeast is needed for the secret lemon message. (a) True (b) False
35. 35.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
36. 36.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) writing the message (c) letting the paper dry (d) reading the message
37. 37.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) only an adult (d) any child
38. 38.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) writing the message (d) putting the iron away
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) a cotton bud (d) turmeric powder
40. 40.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it

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