Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 114 · 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 of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) putting the iron away (d) writing the message
2. 2.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
3. 3.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) ironing the paper (d) writing the message
4. 4.🛟 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
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a balloon (c) white paper (d) lemon juice
6. 6.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
7. 7.🔮 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
8. 8.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) plugging in the iron (c) cutting the lemon (d) ironing the paper
9. 9.True or false: letting the paper dry is a job for an adult. (a) False (b) True
10. 10.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we keep it the same (c) we change it
12. 12.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) a mirror (d) lemon juice
13. 13.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) plugging in the iron (d) reading the message
14. 14.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
15. 15.🍋 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
16. 16.⚖️ 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
17. 17.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
18. 18.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) it gets darker (d) writing stays faint
19. 19.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) white (d) brown
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) turmeric powder (c) an adult with an iron (d) white paper
21. 21.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
22. 22.⚖️ 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 same cotton bud (c) the iron setting (d) how dark the writing is
23. 23.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) magnetic (c) chemical (d) physical
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we measure it (c) we keep it the same
25. 25.True or false: ironing the paper is a job for an adult. (a) True (b) False
26. 26.🔍 Which is the odd one out? (a) reading the message (b) putting the iron away (c) letting the paper dry (d) dipping the cotton bud
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
28. 28.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
29. 29.⚖️ 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 change it (c) we keep it the same
30. 30.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
31. 31.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
32. 32.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) plugging in the iron (d) letting the paper dry
33. 33.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
34. 34.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
35. 35.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, in the dark (d) yes, if cooled
36. 36.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
37. 37.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) whoever is fastest (d) any child
38. 38.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
39. 39.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
40. 40.True or false: white paper is not needed for the secret lemon message. (a) True (b) False

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