Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 668 · 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: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) almost nothing (d) blue words
2. 2.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
3. 3.True or false: putting the iron away is a job for an adult. (a) False (b) True
4. 4.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a cotton bud (c) yeast (d) a mirror
5. 5.🍋 Which of these steps is a job a child can do? (a) writing the message (b) ironing the paper (c) putting the iron away (d) plugging in the iron
6. 6.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) wash your hands (d) rub your eyes
7. 7.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
8. 8.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) reading the message (c) cutting the lemon (d) ironing the paper
9. 9.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
10. 10.⚖️ 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
11. 11.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) an adult with an iron (c) yeast (d) a balloon
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a mirror (d) an adult with an iron
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a magnet (c) an adult with an iron (d) white paper
14. 14.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, in the dark (c) yes, if shaken (d) yes, if cooled
15. 15.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we change it (c) we measure it
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) lemon juice (c) white paper (d) a mirror
18. 18.⚖️ 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
19. 19.True or false: writing the message is a job for an adult. (a) True (b) False
20. 20.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) dipping the cotton bud (c) cutting the lemon (d) plugging in the iron
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) an adult with an iron (d) turmeric powder
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) yeast (c) lemon juice (d) an adult with an iron
23. 23.⚖️ 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 same cotton bud (c) the ironing time (d) the kind of juice
24. 24.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) it turned into air (d) dry juice is see-through
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
26. 26.True or false: plugging in the iron is a job for an adult. (a) True (b) False
27. 27.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
28. 28.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) lemon juice (c) a battery cell (d) a magnet
29. 29.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) letting the paper dry (c) writing the message (d) reading the message
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a cotton bud (d) a battery cell
31. 31.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is sticky (c) it is magnetic (d) it is cold
32. 32.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) magnetic (c) musical (d) physical
33. 33.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
34. 34.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) lemon juice (c) turmeric powder (d) a small bowl
35. 35.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) reading the message (d) ironing the paper
36. 36.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
37. 37.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) letting the paper dry (c) dipping the cotton bud (d) reading the message
38. 38.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) cutting the lemon (d) dipping the cotton bud
39. 39.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) a mirror (c) a battery cell (d) turmeric powder
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) yeast (c) a cotton bud (d) lemon juice

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