Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 682 · 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.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
2. 2.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) lemon juice (c) a balloon (d) a mirror
3. 3.🔍 Which is the odd one out? (a) letting the paper dry (b) plugging in the iron (c) cutting the lemon (d) ironing the paper
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
5. 5.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
6. 6.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) how dark the writing is (c) the kind of juice (d) the same paper
8. 8.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) chemical (d) physical
9. 9.True or false: ironing the paper is a job a child can do. (a) False (b) True
10. 10.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) cutting the lemon (d) writing the message
11. 11.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) writing the message (c) putting the iron away (d) plugging in the iron
12. 12.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) a mirror (d) a small bowl
13. 13.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) reading the message (d) ironing the paper
14. 14.True or false: plugging in the iron is a job for an adult. (a) False (b) True
15. 15.True or false: white paper is needed for the secret lemon message. (a) True (b) False
16. 16.⚖️ 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
17. 17.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, if cooled (d) yes, in the dark
18. 18.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) almost nothing (d) dark brown words
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a magnet (c) white paper (d) a small bowl
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we change it (c) we measure it
21. 21.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
22. 22.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) rub your eyes (c) lick your fingers (d) wash your hands
23. 23.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
24. 24.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the iron is brown (c) paper turns lemony (d) the juice scorches first
25. 25.True or false: plugging in the iron is a job a child can do. (a) False (b) True
26. 26.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) yeast (c) a balloon (d) a magnet
27. 27.True or false: letting the paper dry is a job for an adult. (a) True (b) False
28. 28.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) a small bowl (d) a magnet
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the ironing time (c) the same cotton bud (d) how dark the writing is
30. 30.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) lemon juice (d) yeast
31. 31.🧺 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) a mirror
32. 32.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) dry juice is see-through (d) the ink is magnetic
33. 33.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
34. 34.🔍 Which is the odd one out? (a) writing the message (b) letting the paper dry (c) dipping the cotton bud (d) putting the iron away
35. 35.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
36. 36.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is magnetic (c) it is sticky (d) it can burn skin
37. 37.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
38. 38.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
39. 39.⚖️ 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 measure it (c) we keep it the same
40. 40.True or false: letting the paper dry is a job a child can do. (a) True (b) False

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