Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 997 · 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 the one thing we change? (a) the kind of juice (b) the ironing time (c) the iron setting (d) the same cotton bud
3. 3.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
4. 4.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
5. 5.⚖️ 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
6. 6.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a mirror (c) a magnet (d) an adult with an iron
7. 7.⚖️ 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 keep it the same (c) we change it
8. 8.⚖️ 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
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
10. 10.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) wash your hands (c) skip washing (d) lick your fingers
11. 11.⚖️ 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) True (b) False
12. 12.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) the paper ate it (c) it turned into air (d) dry juice is see-through
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a magnet (c) a small bowl (d) a cotton bud
14. 14.🍋 Which of these steps is a job for an adult? (a) writing the message (b) ironing the paper (c) dipping the cotton bud (d) letting the paper dry
15. 15.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) turmeric powder (d) a small bowl
18. 18.🛟 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
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) lemon juice (d) a battery cell
20. 20.⚖️ 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 measure it (c) we change it
21. 21.True or false: white paper is needed for the secret lemon message. (a) True (b) False
22. 22.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a mirror (c) a cotton bud (d) turmeric powder
23. 23.True or false: a battery cell 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? Which of these is kept the same? (a) how dark the writing is (b) the iron setting (c) the kind of juice
25. 25.True or false: reading the message is a job a child can do. (a) False (b) True
26. 26.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing stays faint (c) it gets darker (d) writing turns green
27. 27.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
30. 30.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) turmeric powder (c) yeast (d) a magnet
31. 31.🧺 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) a cotton bud (d) a balloon
32. 32.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
33. 33.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it can burn skin (d) it is cold
34. 34.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a magnet (c) lemon juice (d) an adult with an iron
35. 35.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a battery cell (c) a cotton bud (d) an adult with an iron
37. 37.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
38. 38.True or false: ironing the paper is a job for an adult. (a) False (b) True
39. 39.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
40. 40.🍋 Which of these steps is a job a child can do? (a) reading the message (b) putting the iron away (c) ironing the paper (d) plugging in the iron

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