Invisible Ink Experiment Worksheet

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

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