Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 191 · 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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a magnet (c) lemon juice (d) white paper
2. 2.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a magnet (c) white paper (d) a balloon
3. 3.🔍 Which is the odd one out? (a) putting the iron away (b) reading the message (c) plugging in the iron (d) cutting the lemon
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we keep it the same (c) we change it
5. 5.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a small bowl (c) a mirror (d) an adult with an iron
6. 6.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) skip washing (d) wash your hands
7. 7.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) plugging in the iron (c) writing the message (d) letting the paper dry
8. 8.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) magnetic (c) physical (d) musical
9. 9.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
10. 10.🔍 Which is the odd one out? (a) letting the paper dry (b) cutting the lemon (c) ironing the paper (d) putting the iron away
11. 11.🧺 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
12. 12.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) writing turns green (c) the paper floats (d) it gets darker
13. 13.⚖️ 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 keep it the same (c) we measure it
14. 14.⚖️ 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 kind of juice (c) the iron setting (d) how dark the writing is
15. 15.⚖️ 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 change it (c) we keep it the same
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
17. 17.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
18. 18.⚖️ 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) True (b) False
19. 19.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) a small bowl (c) white paper (d) a cotton bud
20. 20.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
21. 21.True or false: letting the paper dry is a job for an adult. (a) False (b) True
22. 22.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) blue words (d) almost nothing
23. 23.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) putting the iron away
24. 24.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) an adult with an iron (c) a cotton bud (d) a balloon
26. 26.⚖️ 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
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the ironing time (c) the same cotton bud (d) the same paper
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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) a balloon (d) an adult with an iron
30. 30.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
31. 31.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) writing the message (d) plugging in the iron
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) how dark the writing is (c) the kind of juice
33. 33.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
34. 34.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
35. 35.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
36. 36.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) an adult with an iron (c) a mirror (d) turmeric powder
37. 37.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) reading the message (c) writing the message (d) dipping the cotton bud
38. 38.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) cutting the lemon (c) reading the message (d) ironing the paper
39. 39.⚖️ 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
40. 40.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed

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