Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 284 · 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? What do we do with “the same cotton bud”? (a) we change it (b) we measure it (c) we keep it the same
2. 2.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) writing the message (d) ironing the paper
3. 3.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) wash your hands (d) rub your eyes
4. 4.🔮 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
5. 5.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
6. 6.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
7. 7.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) the paper floats (d) writing stays faint
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) a magnet (d) a small bowl
9. 9.🔍 Which is the odd one out? (a) putting the iron away (b) dipping the cotton bud (c) plugging in the iron (d) ironing the paper
10. 10.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the ink is magnetic (c) the paper ate it (d) it turned into air
11. 11.True or false: writing the message is a job a child can do. (a) False (b) True
12. 12.⚖️ 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
13. 13.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) writing the message (d) ironing the paper
14. 14.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) reading the message (d) putting the iron away
15. 15.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) plugging in the iron (d) cutting the lemon
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) lemon juice (c) a cotton bud (d) white paper
17. 17.🔍 Which is the odd one out? (a) plugging in the iron (b) ironing the paper (c) putting the iron away (d) letting the paper dry
18. 18.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) reading the message (d) cutting the lemon
19. 19.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
20. 20.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a magnet (c) yeast (d) a small bowl
21. 21.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) magnetic (c) chemical (d) physical
22. 22.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) turmeric powder (c) white paper (d) a balloon
23. 23.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
24. 24.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
26. 26.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, if cooled (d) yes, in the dark
27. 27.⚖️ 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 keep it the same (c) we change it
28. 28.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
29. 29.⚖️ 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) how dark the writing is (c) the same paper (d) the kind of juice
30. 30.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) ironing the paper (c) putting the iron away (d) cutting the lemon
31. 31.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) lemon juice (c) white paper (d) a balloon
34. 34.🍋 Which of these steps is a job for an adult? (a) writing the message (b) ironing the paper (c) letting the paper dry (d) dipping the cotton bud
35. 35.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) an adult with an iron (c) a mirror (d) a magnet
36. 36.True or false: cutting the lemon is a job for an adult. (a) False (b) True
37. 37.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
38. 38.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) white paper (c) an adult with an iron (d) a cotton bud
39. 39.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
40. 40.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it

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