Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 337 · 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 a child can do? (a) plugging in the iron (b) putting the iron away (c) reading the message (d) cutting the lemon
2. 2.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
3. 3.⚖️ 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
4. 4.🔍 Which is the odd one out? (a) putting the iron away (b) letting the paper dry (c) dipping the cotton bud (d) writing the message
5. 5.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it can burn skin (c) it is sticky (d) it is cold
6. 6.🔮 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
7. 7.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a magnet (c) a small bowl (d) an adult with an iron
8. 8.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) cutting the lemon (d) dipping the cotton bud
9. 9.⚖️ 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
10. 10.True or false: putting the iron away is a job for an adult. (a) False (b) True
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) an adult with an iron (c) white paper (d) lemon juice
12. 12.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) writing the message (d) plugging in the iron
13. 13.⚖️ 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 iron setting (d) the same cotton bud
14. 14.⚖️ 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 measure it (c) we change it
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a magnet (c) white paper (d) lemon juice
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False
17. 17.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) magnetic (c) physical (d) chemical
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) True (b) False
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) a mirror (d) lemon juice
20. 20.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
21. 21.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
22. 22.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
23. 23.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing turns green (d) writing stays faint
24. 24.⚖️ 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
25. 25.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a battery cell (c) a cotton bud (d) a magnet
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same cotton bud (b) how dark the writing is (c) the kind of juice
27. 27.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a battery cell (c) an adult with an iron (d) a magnet
28. 28.🛟 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
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the iron setting (c) the ironing time (d) how dark the writing is
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
31. 31.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) plugging in the iron (d) letting the paper dry
32. 32.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
33. 33.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
34. 34.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) reading the message (d) putting the iron away
35. 35.⚖️ 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 keep it the same (c) we change it
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) white paper (d) turmeric powder
37. 37.⚖️ 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
38. 38.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
39. 39.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
40. 40.True or false: letting the paper dry is a job for an adult. (a) True (b) False

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