Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 53 · 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.🔍 Which is the odd one out? (a) letting the paper dry (b) reading the message (c) writing the message (d) ironing the paper
2. 2.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
3. 3.True or false: plugging in the iron is a job for an adult. (a) False (b) True
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) lemon juice (d) a magnet
5. 5.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) no, it stays brown (d) yes, if shaken
6. 6.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
7. 7.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
8. 8.🔍 Which is the odd one out? (a) writing the message (b) plugging in the iron (c) reading the message (d) dipping the cotton bud
9. 9.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
10. 10.True or false: cutting the lemon is a job a child can do. (a) True (b) False
11. 11.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing stays faint (c) writing turns green (d) it gets darker
12. 12.🧺 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) white paper (d) a balloon
13. 13.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
15. 15.⚖️ 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
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) how dark the writing is (c) the same cotton bud (d) the ironing time
17. 17.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) almost nothing (c) a rainbow (d) dark brown words
18. 18.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
19. 19.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) white paper (c) yeast (d) a battery cell
20. 20.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) chemical (d) musical
21. 21.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
22. 22.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
23. 23.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) cutting the lemon (c) reading the message (d) ironing the paper
24. 24.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
25. 25.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
26. 26.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
27. 27.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) the juice scorches first (d) heat adds colour
28. 28.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) writing the message (c) plugging in the iron (d) cutting the lemon
29. 29.True or false: letting the paper dry is a job for an adult. (a) True (b) False
30. 30.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) a cotton bud (c) a small bowl (d) white paper
31. 31.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
32. 32.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) the ink is magnetic (d) dry juice is see-through
33. 33.⚖️ 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 kind of juice (c) the same paper
34. 34.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) writing the message (d) ironing the paper
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) True (b) False
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) yeast (c) a small bowl (d) white paper
37. 37.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
38. 38.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) white (c) green (d) brown
39. 39.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) reading the message (d) ironing the paper
40. 40.🔍 Which is the odd one out? (a) plugging in the iron (b) dipping the cotton bud (c) ironing the paper (d) cutting the lemon

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