Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 387 · 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.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
2. 2.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) a cotton bud (c) lemon juice (d) an adult with an iron
3. 3.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
4. 4.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) whoever is fastest (c) any child (d) the youngest child
5. 5.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) a rainbow (c) blue words (d) dark brown words
6. 6.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing stays faint (d) writing turns green
7. 7.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
8. 8.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) putting the iron away (d) reading the message
9. 9.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the ink is magnetic (c) the paper ate it (d) dry juice is see-through
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) a battery cell (d) a small bowl
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a magnet (c) an adult with an iron (d) lemon juice
12. 12.🍋 Which of these steps is a job for an adult? (a) reading the message (b) putting the iron away (c) letting the paper dry (d) writing the message
13. 13.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) ironing the paper (d) dipping the cotton bud
14. 14.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a mirror (c) a balloon (d) a small bowl
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the kind of juice (c) how dark the writing is (d) the iron setting
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 measure it (c) we keep it the same
17. 17.⚖️ 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
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) an adult with an iron (c) a balloon (d) a small bowl
19. 19.⚖️ 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 iron setting (c) the kind of juice
20. 20.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) reading the message (c) dipping the cotton bud (d) letting the paper dry
21. 21.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) letting the paper dry (d) cutting the lemon
22. 22.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) writing the message
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) white paper (c) a cotton bud (d) lemon juice
24. 24.True or false: white paper is needed for the secret lemon message. (a) False (b) True
25. 25.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) physical (c) magnetic (d) chemical
26. 26.True or false: cutting the lemon is a job for an adult. (a) False (b) True
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) a cotton bud (c) white paper (d) a small bowl
28. 28.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) rub your eyes (c) skip washing (d) lick your fingers
29. 29.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) yeast (c) white paper (d) an adult with an iron
30. 30.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
31. 31.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
32. 32.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
33. 33.⚖️ 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
34. 34.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) yes, if shaken (d) no, it stays brown
35. 35.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a magnet (c) a cotton bud (d) an adult with an iron
37. 37.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) writing the message (c) reading the message (d) dipping the cotton bud
38. 38.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
39. 39.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
40. 40.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it

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