Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 885 · 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.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
2. 2.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) chemical (d) physical
3. 3.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) lemon juice (c) a small bowl (d) white paper
5. 5.⚖️ 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) the ironing time (c) how dark the writing is
6. 6.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
7. 7.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a magnet (c) yeast (d) a mirror
8. 8.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
9. 9.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
10. 10.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the paper ate it (c) it turned into air (d) the ink is magnetic
11. 11.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
12. 12.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) lemon juice (d) a balloon
13. 13.True or false: plugging in the iron is a job a child can do. (a) False (b) True
14. 14.True or false: white paper is needed for the secret lemon message. (a) True (b) False
15. 15.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
16. 16.True or false: putting the iron away is a job a child can do. (a) False (b) True
17. 17.🔍 Which is the odd one out? (a) plugging in the iron (b) writing the message (c) cutting the lemon (d) ironing the paper
18. 18.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) lemon juice (c) a mirror (d) turmeric powder
19. 19.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it is magnetic (d) it can burn skin
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) a small bowl (c) white paper (d) a cotton bud
21. 21.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
22. 22.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) dipping the cotton bud (d) cutting the lemon
23. 23.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a magnet (c) lemon juice (d) an adult with an iron
24. 24.True or false: cutting the lemon 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? Which of these is what we measure? (a) the ironing time (b) the iron setting (c) the kind of juice (d) how dark the writing is
26. 26.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
27. 27.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) only an adult (d) the youngest child
28. 28.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
29. 29.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the iron setting (c) the kind of juice (d) the same paper
31. 31.True or false: yeast is needed for the secret lemon message. (a) True (b) False
32. 32.True or false: cutting the lemon is a job for an adult. (a) True (b) False
33. 33.⚖️ 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
34. 34.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
35. 35.True or false: ironing the paper is a job for an adult. (a) False (b) True
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) an adult with an iron (c) white paper (d) lemon juice
37. 37.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) a rainbow (d) almost nothing
38. 38.🔮 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
39. 39.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
40. 40.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) putting the iron away (d) writing the message

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