Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 794 · 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) almost nothing (b) a rainbow (c) blue words (d) dark brown words
2. 2.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a battery cell (c) a small bowl (d) yeast
3. 3.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a mirror (c) a balloon (d) white paper
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the same paper
5. 5.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
6. 6.⚖️ 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
7. 7.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) writing the message (d) putting the iron away
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a balloon (c) an adult with an iron (d) lemon juice
9. 9.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) putting the iron away (d) writing the message
10. 10.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
11. 11.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
12. 12.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
13. 13.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we change it (c) we measure it
15. 15.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
16. 16.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
17. 17.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) rub your eyes (d) wash your hands
18. 18.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) plugging in the iron (c) letting the paper dry (d) reading the message
19. 19.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
20. 20.⚖️ 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
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) a mirror (d) a small bowl
22. 22.🛟 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
23. 23.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) writing the message (d) cutting the lemon
24. 24.True or false: writing the message is a job a child can do. (a) True (b) False
25. 25.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) writing turns green (c) it gets darker (d) the paper floats
26. 26.🔍 Which is the odd one out? (a) writing the message (b) ironing the paper (c) dipping the cotton bud (d) letting the paper dry
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the same cotton bud (c) the iron setting (d) the kind of juice
28. 28.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) white paper (c) a small bowl (d) lemon juice
30. 30.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) the juice scorches first (c) heat adds colour (d) paper turns lemony
31. 31.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) putting the iron away (d) ironing the paper
32. 32.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
33. 33.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
34. 34.⚖️ 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
35. 35.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) reading the message (d) plugging in the iron
36. 36.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
37. 37.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
38. 38.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) whoever is fastest (d) the youngest child
39. 39.True or false: ironing the paper is a job a child can do. (a) False (b) True
40. 40.True or false: cutting the lemon is a job for an adult. (a) True (b) False

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