Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 376 · 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: ironing the paper is a job for an adult. (a) False (b) True
2. 2.🍋 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
3. 3.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) rub your eyes (c) wash your hands (d) lick your fingers
4. 4.🍋 Secret message: who does this step — plugging in the iron? (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? Which of these is the one thing we change? (a) the same cotton bud (b) the kind of juice (c) the iron setting (d) how dark the writing is
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we measure it (c) we keep it the same
7. 7.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) no, it stays brown (d) yes, if cooled
8. 8.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
9. 9.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) dipping the cotton bud (d) plugging in the iron
10. 10.True or false: letting the paper dry is a job for an adult. (a) True (b) False
11. 11.⚖️ 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
12. 12.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we keep it the same (c) we measure it
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
15. 15.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) a small bowl (c) a cotton bud (d) white paper
16. 16.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) whoever is fastest (d) only an adult
17. 17.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
18. 18.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
19. 19.True or false: writing the message is a job a child can do. (a) True (b) False
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) a magnet (d) an adult with an iron
21. 21.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
22. 22.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) a rainbow (d) almost nothing
23. 23.⚖️ 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) False (b) True
24. 24.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
25. 25.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the iron is brown (c) the juice scorches first (d) heat adds colour
26. 26.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
27. 27.True or false: a mirror 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? What do we do with “the ironing time”? (a) we keep it the same (b) we change it (c) we measure it
29. 29.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
30. 30.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) an adult with an iron (c) a magnet (d) lemon juice
31. 31.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
32. 32.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
33. 33.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a magnet (c) a cotton bud (d) a battery cell
34. 34.True or false: cutting the lemon is a job for an adult. (a) True (b) False
35. 35.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) blue (c) green (d) white
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) False (b) True
37. 37.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) white paper (c) a cotton bud (d) a battery cell
38. 38.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) letting the paper dry (c) writing the message (d) dipping the cotton bud
39. 39.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the same paper (c) the ironing time (d) the kind of juice

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