Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 428 · 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 steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) reading the message (d) ironing the paper
2. 2.⚖️ 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
3. 3.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
4. 4.True or false: white paper is needed for the secret lemon message. (a) False (b) True
5. 5.True or false: writing the message is a job a child can do. (a) False (b) True
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a mirror (c) a cotton bud (d) lemon juice
7. 7.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
8. 8.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) dark brown words (c) almost nothing (d) blue words
9. 9.True or false: ironing the paper is a job a child can do. (a) True (b) False
10. 10.True or false: reading the message is a job a child can do. (a) True (b) False
11. 11.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
12. 12.⚖️ 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 change it (c) we keep it the same
13. 13.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
14. 14.⚖️ 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) the kind of juice (c) the ironing time (d) the same cotton bud
15. 15.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) white (c) green (d) brown
16. 16.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a magnet (c) an adult with an iron (d) white paper
18. 18.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
19. 19.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) skip washing (d) wash your hands
20. 20.True or false: ironing the paper is a job for an adult. (a) True (b) False
21. 21.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
22. 22.⚖️ 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) how dark the writing is (c) the same paper
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) white paper (c) an adult with an iron (d) lemon juice
24. 24.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a magnet (c) a balloon (d) a small bowl
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we change it (c) we keep it the same
26. 26.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) any child (d) only an adult
27. 27.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing turns green (d) writing stays faint
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we measure it (c) we keep it the same
29. 29.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
30. 30.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) an adult with an iron (c) turmeric powder (d) lemon juice
31. 31.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) plugging in the iron (c) letting the paper dry (d) reading the message
32. 32.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) no, it stays brown (c) yes, in the dark (d) yes, if shaken
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we keep it the same (c) we change it
35. 35.⚖️ 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 same cotton bud (c) the kind of juice
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) an adult with an iron (c) a cotton bud (d) lemon juice
37. 37.True or false: letting the paper dry is a job for an adult. (a) False (b) True
38. 38.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
39. 39.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False

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