Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 207 · 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.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
2. 2.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) writing stays faint (d) the paper floats
3. 3.⚖️ 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 measure it (c) we keep it the same
4. 4.True or false: plugging in the iron is a job a child can do. (a) True (b) False
5. 5.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) putting the iron away (c) plugging in the iron (d) cutting the lemon
6. 6.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) it turned into air (c) the ink is magnetic (d) the paper ate it
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) white paper (c) a cotton bud (d) lemon juice
8. 8.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
9. 9.True or false: putting the iron away is a job a child can do. (a) True (b) False
10. 10.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
11. 11.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) any child (c) whoever is fastest (d) the youngest child
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we measure it (c) we change it
13. 13.🔍 Which is the odd one out? (a) cutting the lemon (b) reading the message (c) ironing the paper (d) putting the iron away
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we keep it the same (c) we change it
15. 15.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
16. 16.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a magnet (c) a mirror (d) white paper
17. 17.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
18. 18.🔮 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
19. 19.True or false: plugging in the iron is a job for an adult. (a) True (b) False
20. 20.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a small bowl (c) a cotton bud (d) a mirror
21. 21.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) writing the message (d) putting the iron away
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) a battery cell (d) a small bowl
23. 23.⚖️ 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
24. 24.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) cutting the lemon (d) writing the message
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) how dark the writing is (c) the same cotton bud (d) the iron setting
26. 26.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) white paper (c) lemon juice (d) a magnet
27. 27.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
28. 28.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) reading the message (c) cutting the lemon (d) putting the iron away
29. 29.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) musical (c) magnetic (d) chemical
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the same cotton bud
31. 31.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) writing the message (c) plugging in the iron (d) ironing the paper
32. 32.True or false: reading the message is a job a child can do. (a) False (b) True
33. 33.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
34. 34.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
36. 36.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) skip washing (c) lick your fingers (d) rub your eyes
37. 37.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a balloon (c) lemon juice (d) an adult with an iron
38. 38.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
39. 39.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) a small bowl (d) turmeric powder

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