Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 264 · 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: dipping the cotton bud is a job for an adult. (a) True (b) False
2. 2.True or false: cutting the lemon is a job for an adult. (a) False (b) True
3. 3.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) ironing the paper (d) reading the message
4. 4.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) only an adult (d) the youngest child
5. 5.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) brown (d) white
6. 6.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a balloon (c) a battery cell (d) lemon juice
7. 7.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is cold (c) it is magnetic (d) it is sticky
8. 8.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
9. 9.⚖️ 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 measure it (c) we change it
10. 10.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) the paper floats (d) writing stays faint
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a mirror (c) an adult with an iron (d) white paper
12. 12.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
13. 13.🔮 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
14. 14.True or false: letting the paper dry is a job for an adult. (a) False (b) True
15. 15.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
16. 16.⚖️ 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 cotton bud (d) the same paper
17. 17.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
18. 18.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) heat adds colour (d) the juice scorches first
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) False (b) True
20. 20.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) turmeric powder (c) a cotton bud (d) an adult with an iron
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a balloon (d) a cotton bud
22. 22.🧺 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) turmeric powder (d) a cotton bud
23. 23.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) letting the paper dry (d) cutting the lemon
24. 24.🍋 Which of these steps is a job for an adult? (a) writing the message (b) cutting the lemon (c) letting the paper dry (d) reading the message
25. 25.⚖️ 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 keep it the same (c) we change it
26. 26.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) a mirror (d) white paper
27. 27.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) plugging in the iron (c) reading the message (d) writing the message
28. 28.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
29. 29.True or false: yeast is needed for the secret lemon message. (a) False (b) True
30. 30.🍋 Which of these steps is a job a child can do? (a) writing the message (b) ironing the paper (c) plugging in the iron (d) putting the iron away
31. 31.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the paper ate it (c) it turned into air (d) the ink is magnetic
32. 32.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
33. 33.True or false: ironing the paper is a job a child can do. (a) False (b) True
34. 34.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) almost nothing (d) dark brown words
35. 35.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) an adult with an iron (d) turmeric powder
36. 36.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
37. 37.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) rub your eyes (d) wash your hands
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the same cotton bud (c) the kind of juice (d) the ironing time
39. 39.True or false: white paper is needed for the secret lemon message. (a) True (b) False
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False

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