Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 791 · 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 magnet is needed for the secret lemon message. (a) True (b) False
2. 2.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it is magnetic (d) it can burn skin
3. 3.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) dipping the cotton bud (d) plugging in the iron
4. 4.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) a rainbow (c) dark brown words (d) blue words
5. 5.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) rub your eyes (c) lick your fingers (d) skip washing
6. 6.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
7. 7.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) writing stays faint (c) the paper floats (d) it gets darker
8. 8.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) a magnet (d) white paper
10. 10.⚖️ 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 ironing time (c) the iron setting (d) the kind of juice
11. 11.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
12. 12.🍋 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
13. 13.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) putting the iron away (d) reading the message
14. 14.🧺 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) yeast
15. 15.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) green (c) white (d) blue
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) an adult with an iron (c) a balloon (d) white paper
17. 17.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
18. 18.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a balloon (c) yeast (d) a battery cell
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.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) the kind of juice (c) how dark the writing is
21. 21.🧺 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) turmeric powder
22. 22.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) cutting the lemon (d) writing the message
23. 23.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a balloon (c) lemon juice (d) yeast
24. 24.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a small bowl (c) a balloon (d) turmeric powder
25. 25.⚖️ 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
26. 26.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) the paper ate it (d) dry juice is see-through
27. 27.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
28. 28.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) a mirror (d) a cotton bud
29. 29.⚖️ 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 change it (c) we keep it the same
30. 30.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
31. 31.🔮 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
32. 32.⚖️ 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
33. 33.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
34. 34.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) lemon juice (c) a magnet (d) an adult with an iron
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) an adult with an iron (d) a battery cell
37. 37.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
38. 38.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) whoever is fastest (d) any child
39. 39.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
40. 40.⚖️ 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 kind of juice (c) the same paper (d) the iron setting

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