Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 547 · 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? What do we do with “the iron setting”? (a) we keep it the same (b) we measure it (c) we change it
2. 2.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we measure it (c) we change it
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
5. 5.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) letting the paper dry (c) ironing the paper (d) putting the iron away
6. 6.⚖️ 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 paper (c) the ironing time (d) the same cotton bud
7. 7.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) dipping the cotton bud (d) ironing the paper
8. 8.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) cutting the lemon (d) dipping the cotton bud
9. 9.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a small bowl (d) yeast
11. 11.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) dry juice is see-through (c) the paper ate it (d) it turned into air
12. 12.🍋 Which of these steps is a job for an adult? (a) reading the message (b) plugging in the iron (c) writing the message (d) dipping the cotton bud
13. 13.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) only an adult (d) any child
14. 14.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) writing turns green (c) it gets darker (d) the paper floats
15. 15.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
16. 16.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
17. 17.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
18. 18.True or false: ironing the paper is a job a child can do. (a) True (b) False
19. 19.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
20. 20.⚖️ 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
21. 21.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) cutting the lemon (c) reading the message (d) ironing the paper
22. 22.🔍 Which is the odd one out? (a) letting the paper dry (b) ironing the paper (c) cutting the lemon (d) plugging in the iron
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) the kind of juice (c) how dark the writing is
24. 24.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) False (b) True
26. 26.⚖️ 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
27. 27.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) yeast (c) lemon juice (d) white paper
28. 28.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
29. 29.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
30. 30.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
31. 31.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) dark brown words (d) almost nothing
32. 32.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if cooled (d) yes, if shaken
33. 33.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
34. 34.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) a balloon (d) white paper
35. 35.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it is cold (d) it can burn skin
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) lemon juice (c) a small bowl (d) turmeric powder
37. 37.⚖️ 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 keep it the same (c) we measure it
38. 38.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
39. 39.⚖️ 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
40. 40.🔍 Which is the odd one out? (a) reading the message (b) ironing the paper (c) cutting the lemon (d) putting the iron away

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