Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 660 · 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: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing turns green (d) writing stays faint
2. 2.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a balloon (c) a magnet (d) lemon juice
3. 3.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) white paper (c) an adult with an iron (d) a cotton bud
5. 5.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
6. 6.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
7. 7.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, if cooled (c) no, it stays brown (d) yes, in the dark
8. 8.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) letting the paper dry (c) reading the message (d) dipping the cotton bud
9. 9.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
10. 10.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) False (b) True
12. 12.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
13. 13.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) dipping the cotton bud (c) writing the message (d) letting the paper dry
14. 14.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) ironing the paper (d) writing the message
15. 15.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is sticky (c) it can burn skin (d) it is magnetic
16. 16.⚖️ 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
17. 17.True or false: reading the message is a job a child can do. (a) False (b) True
18. 18.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) paper turns lemony (c) the juice scorches first (d) the iron is brown
19. 19.True or false: cutting the lemon is a job a child can do. (a) True (b) False
20. 20.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) writing the message (c) dipping the cotton bud (d) reading the message
21. 21.True or false: putting the iron away is a job for an adult. (a) True (b) False
22. 22.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) yeast (c) a small bowl (d) a cotton bud
23. 23.⚖️ 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
24. 24.True or false: letting the paper dry is a job a child can do. (a) True (b) False
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a mirror (c) an adult with an iron (d) white paper
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) an adult with an iron (d) turmeric powder
27. 27.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) dry juice is see-through (c) the ink is magnetic (d) it turned into air
28. 28.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) rub your eyes (d) wash your hands
29. 29.⚖️ 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) the same paper (c) the kind of juice (d) how dark the writing is
30. 30.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) chemical (d) physical
31. 31.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) green (c) brown (d) blue
32. 32.True or false: writing the message is a job for an adult. (a) False (b) True
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a balloon (c) a small bowl (d) an adult with an iron
34. 34.🔮 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
35. 35.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) a balloon (d) a battery cell
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False
37. 37.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
38. 38.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
39. 39.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) white paper (d) a balloon

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