Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 653 · 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: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) dark brown words (c) blue words (d) almost nothing
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) True (b) False
3. 3.⚖️ 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
4. 4.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a balloon (c) a cotton bud (d) an adult with an iron
6. 6.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a small bowl (c) lemon juice (d) turmeric powder
7. 7.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) lemon juice (c) an adult with an iron (d) white paper
9. 9.⚖️ 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
10. 10.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
11. 11.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
12. 12.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) no, it stays brown (c) yes, if shaken (d) yes, in the dark
13. 13.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) cutting the lemon (c) ironing the paper (d) plugging in the iron
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) white paper (c) lemon juice (d) an adult with an iron
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
17. 17.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
18. 18.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing stays faint (d) writing turns green
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) yeast (c) white paper (d) an adult with an iron
20. 20.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) an adult with an iron (c) lemon juice (d) a battery cell
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) a mirror (d) lemon juice
22. 22.True or false: letting the paper dry is a job a child can do. (a) False (b) True
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) the kind of juice (c) how dark the writing is
24. 24.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
25. 25.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) dipping the cotton bud (c) letting the paper dry (d) reading the message
26. 26.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) wash your hands (d) rub your eyes
27. 27.True or false: writing the message is a job for an adult. (a) True (b) False
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) a magnet (d) white paper
29. 29.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) putting the iron away (c) ironing the paper (d) cutting the lemon
30. 30.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
31. 31.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a magnet (c) white paper (d) turmeric powder
32. 32.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
33. 33.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) letting the paper dry (d) ironing the paper
34. 34.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) the youngest child (d) whoever is fastest
35. 35.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
36. 36.True or false: plugging in the iron is a job a child can do. (a) True (b) False
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) the kind of juice (c) the same cotton bud (d) the same paper
38. 38.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
39. 39.🔍 Which is the odd one out? (a) letting the paper dry (b) reading the message (c) cutting the lemon (d) dipping the cotton bud
40. 40.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed

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