Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 837 · 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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) a balloon (d) white paper
2. 2.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) wash your hands (c) lick your fingers (d) skip washing
3. 3.🔍 Which is the odd one out? (a) reading the message (b) dipping the cotton bud (c) cutting the lemon (d) letting the paper dry
4. 4.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) any child (d) the youngest child
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) an adult with an iron (d) a magnet
6. 6.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) putting the iron away (d) letting the paper dry
7. 7.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
8. 8.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) magnetic (c) physical (d) chemical
9. 9.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
10. 10.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing stays faint (d) writing turns green
11. 11.True or false: letting the paper dry is a job a child can do. (a) True (b) False
12. 12.True or false: plugging in the iron is a job for an adult. (a) True (b) False
13. 13.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
14. 14.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we change it (c) we keep it the same
16. 16.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) brown (c) white (d) blue
17. 17.True or false: cutting the lemon is a job a child can do. (a) True (b) False
18. 18.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) almost nothing (d) a rainbow
19. 19.True or false: cutting the lemon is a job for an adult. (a) True (b) False
20. 20.True or false: ironing the paper is a job a child can do. (a) True (b) False
21. 21.🔍 Which is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) plugging in the iron (d) cutting the lemon
22. 22.True or false: reading the message is a job for an adult. (a) False (b) True
23. 23.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
24. 24.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
25. 25.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
26. 26.True or false: reading the message is a job a child can do. (a) False (b) True
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) white paper (c) an adult with an iron (d) lemon juice
28. 28.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
29. 29.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) dry juice is see-through (d) the paper ate it
30. 30.True or false: yeast is needed for the secret lemon message. (a) False (b) True
31. 31.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) ironing the paper (d) letting the paper dry
32. 32.⚖️ 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) True (b) False
33. 33.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
34. 34.True or false: writing the message is a job a child can do. (a) True (b) False
35. 35.True or false: writing the message is a job for an adult. (a) False (b) True
36. 36.⚖️ 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
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we keep it the same (c) we change it
38. 38.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) a battery cell (d) a small bowl
39. 39.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) lemon juice (c) yeast (d) a mirror
40. 40.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) no, it stays brown (d) yes, if cooled

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