Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 943 · 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: the adult irons for only one second. What happens? (a) the paper floats (b) writing stays faint (c) writing turns green (d) it gets darker
2. 2.⚖️ 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
3. 3.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) wash your hands (c) skip washing (d) lick your fingers
4. 4.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a battery cell (c) a magnet (d) a small bowl
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) an adult with an iron (d) yeast
6. 6.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
7. 7.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is magnetic (d) it is sticky
8. 8.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
10. 10.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) almost nothing (d) a rainbow
11. 11.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
12. 12.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
13. 13.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) writing the message (d) cutting the lemon
14. 14.🔍 Which is the odd one out? (a) writing the message (b) putting the iron away (c) letting the paper dry (d) reading the message
15. 15.⚖️ 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
16. 16.⚖️ 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 keep it the same (c) we measure it
17. 17.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
18. 18.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a battery cell (d) an adult with an iron
20. 20.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
21. 21.True or false: putting the iron away is a job for an adult. (a) True (b) False
22. 22.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) ironing the paper (d) letting the paper dry
23. 23.⚖️ 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 ironing time (c) how dark the writing is (d) the same paper
24. 24.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) white paper (c) a cotton bud (d) a small bowl
26. 26.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a magnet (c) a mirror (d) a cotton bud
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) False (b) True
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we change it (c) we measure it
29. 29.⚖️ 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) False (b) True
30. 30.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) any child (d) whoever is fastest
31. 31.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
32. 32.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
33. 33.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) dipping the cotton bud (d) ironing the paper
34. 34.⚖️ 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 kind of juice (c) the same paper
35. 35.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) reading the message (d) plugging in the iron
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a balloon (c) lemon juice (d) a small bowl
37. 37.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) physical (c) magnetic (d) musical
38. 38.True or false: cutting the lemon is a job a child can do. (a) False (b) True
39. 39.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
40. 40.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False

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