Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 573 · 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.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) skip washing (c) rub your eyes (d) lick your fingers
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a small bowl (d) a mirror
3. 3.⚖️ 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 kind of juice (c) the iron setting
4. 4.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) letting the paper dry (d) cutting the lemon
5. 5.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) letting the paper dry (c) dipping the cotton bud (d) reading the message
6. 6.True or false: cutting the lemon is a job a child can do. (a) False (b) True
7. 7.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) an adult with an iron (c) turmeric powder (d) a mirror
8. 8.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
9. 9.🔮 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
10. 10.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) any child (d) only an adult
11. 11.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
12. 12.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) turmeric powder (c) an adult with an iron (d) a cotton bud
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we change it (c) we measure it
14. 14.⚖️ 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 kind of juice (c) the same cotton bud
15. 15.⚖️ 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
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) how dark the writing is (c) the same paper (d) the same cotton bud
17. 17.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) blue (c) white (d) green
18. 18.🧺 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 battery cell (d) a small bowl
19. 19.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
20. 20.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) dipping the cotton bud (d) ironing the paper
21. 21.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if cooled (c) no, it stays brown (d) yes, if shaken
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
23. 23.🧺 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) lemon juice
24. 24.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) reading the message (d) putting the iron away
25. 25.⚖️ 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
26. 26.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) dark brown words (c) almost nothing (d) blue words
27. 27.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) cutting the lemon (d) dipping the cotton bud
28. 28.🔍 Which is the odd one out? (a) writing the message (b) cutting the lemon (c) putting the iron away (d) ironing the paper
29. 29.True or false: reading the message is a job for an adult. (a) False (b) True
30. 30.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
32. 32.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) writing the message (d) plugging in the iron
33. 33.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) yeast (c) a magnet (d) a small bowl
34. 34.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) white paper (c) a battery cell (d) a small bowl
36. 36.True or false: letting the paper dry is a job a child can do. (a) False (b) True
37. 37.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
38. 38.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
39. 39.🧺 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) turmeric powder
40. 40.⚖️ 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 measure it (c) we change it

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