Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 786 · 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.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) the paper floats (d) writing stays faint
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a mirror (c) an adult with an iron (d) white paper
3. 3.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
4. 4.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) wash your hands (c) lick your fingers (d) rub your eyes
5. 5.🔍 Which is the odd one out? (a) cutting the lemon (b) letting the paper dry (c) dipping the cotton bud (d) writing the message
6. 6.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) an adult with an iron (c) turmeric powder (d) a battery cell
7. 7.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) a magnet (d) an adult with an iron
8. 8.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
9. 9.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) a rainbow (d) almost nothing
10. 10.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) white paper (c) a battery cell (d) a magnet
11. 11.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) dipping the cotton bud (d) ironing the paper
12. 12.True or false: writing the message is a job for an adult. (a) True (b) False
13. 13.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
14. 14.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a cotton bud (d) a balloon
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the same cotton bud (c) the iron setting (d) the ironing time
17. 17.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
18. 18.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is sticky (c) it is cold (d) it is magnetic
19. 19.True or false: letting the paper dry is a job a child can do. (a) True (b) False
20. 20.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
21. 21.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the ink is magnetic (c) the paper ate it (d) dry juice is see-through
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
23. 23.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
24. 24.True or false: cutting the lemon is a job for an adult. (a) False (b) True
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) False (b) True
26. 26.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
27. 27.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if cooled (c) yes, if shaken (d) no, it stays brown
28. 28.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) letting the paper dry (d) cutting the lemon
29. 29.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
31. 31.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) the iron is brown (c) heat adds colour (d) paper turns lemony
32. 32.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
33. 33.True or false: reading the message is a job a child can do. (a) False (b) True
34. 34.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) ironing the paper (c) putting the iron away (d) plugging in the iron
35. 35.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
36. 36.⚖️ 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 change it (c) we measure it
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) an adult with an iron (d) a magnet
39. 39.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) yeast (c) a small bowl (d) lemon juice
40. 40.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it

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