Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 684 · 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) almost nothing (c) blue words (d) a rainbow
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) the kind of juice (c) how dark the writing is
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a mirror (c) a cotton bud (d) lemon juice
4. 4.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is magnetic (c) it is sticky (d) it is cold
5. 5.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
6. 6.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) ironing the paper (d) reading the message
7. 7.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
8. 8.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) plugging in the iron (d) writing the message
9. 9.True or false: letting the paper dry is a job for an adult. (a) False (b) True
10. 10.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
11. 11.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a battery cell (c) a mirror (d) white paper
12. 12.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
13. 13.True or false: putting the iron away is a job for an adult. (a) False (b) True
14. 14.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) letting the paper dry (d) plugging in the iron
15. 15.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we keep it the same (c) we measure it
17. 17.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
18. 18.True or false: ironing the paper is a job a child can do. (a) True (b) False
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) an adult with an iron (c) lemon juice (d) a cotton bud
20. 20.True or false: plugging in the iron is a job a child can do. (a) True (b) False
21. 21.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
22. 22.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a magnet (c) lemon juice (d) a small bowl
23. 23.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
25. 25.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) it gets darker (c) writing turns green (d) the paper floats
26. 26.⚖️ 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 change it (c) we keep it the same
27. 27.True or false: writing the message is a job for an adult. (a) False (b) True
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we keep it the same (c) we measure it
29. 29.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
30. 30.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
31. 31.⚖️ 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
32. 32.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) cutting the lemon (d) letting the paper dry
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) yeast (d) white paper
34. 34.⚖️ 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
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we keep it the same (c) we change it
36. 36.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) letting the paper dry (d) cutting the lemon
37. 37.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we change it (c) we measure it
39. 39.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) wash your hands (c) rub your eyes (d) lick your fingers
40. 40.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed

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