Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 320 · 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) blue words (b) almost nothing (c) a rainbow (d) dark brown words
2. 2.⚖️ 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
3. 3.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
4. 4.🔍 Which is the odd one out? (a) reading the message (b) ironing the paper (c) cutting the lemon (d) plugging in the iron
5. 5.⚖️ 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
6. 6.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) writing the message (c) reading the message (d) letting the paper dry
7. 7.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) dry juice is see-through (d) the paper ate it
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) white paper (d) a battery cell
9. 9.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
10. 10.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) turmeric powder (c) lemon juice (d) a battery cell
11. 11.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is magnetic (c) it is cold (d) it is sticky
12. 12.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
13. 13.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the kind of juice (c) the iron setting (d) the same paper
15. 15.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
16. 16.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a mirror (c) lemon juice (d) white paper
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) turmeric powder (c) a small bowl (d) white paper
19. 19.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a magnet (c) a balloon (d) a cotton bud
20. 20.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
21. 21.🍋 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) dipping the cotton bud
22. 22.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a balloon (c) lemon juice (d) an adult with an iron
23. 23.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
24. 24.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) putting the iron away (d) writing the message
25. 25.🔍 Which is the odd one out? (a) cutting the lemon (b) writing the message (c) putting the iron away (d) ironing the paper
26. 26.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
27. 27.🛟 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
28. 28.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
29. 29.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
30. 30.True or false: putting the iron away is a job a child can do. (a) False (b) True
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we measure it (c) we keep it the same
32. 32.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) chemical (d) musical
33. 33.🍋 Which of these steps is a job for an adult? (a) reading the message (b) ironing the paper (c) dipping the cotton bud (d) writing the message
34. 34.True or false: ironing the paper is a job for an adult. (a) False (b) True
35. 35.True or false: cutting the lemon is a job a child can do. (a) False (b) True
36. 36.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) reading the message (c) putting the iron away (d) ironing the paper
37. 37.⚖️ 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
38. 38.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) the same paper (c) the kind of juice (d) how dark the writing is
40. 40.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if shaken (d) yes, if cooled

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