Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 600 · 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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a magnet (c) lemon juice (d) a cotton bud
2. 2.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
3. 3.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
4. 4.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
5. 5.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) cutting the lemon (d) writing the message
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.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) white paper (c) a balloon (d) yeast
8. 8.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) a small bowl (d) a magnet
9. 9.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) wash your hands (c) rub your eyes (d) lick your fingers
10. 10.⚖️ 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
11. 11.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) writing the message (d) putting the iron away
12. 12.True or false: letting the paper dry is a job for an adult. (a) False (b) True
13. 13.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) writing the message (d) plugging in the iron
14. 14.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) chemical (d) physical
15. 15.True or false: cutting the lemon is a job for an adult. (a) True (b) False
16. 16.True or false: plugging in the iron is a job a child can do. (a) True (b) False
17. 17.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is cold (c) it is sticky (d) it is magnetic
18. 18.⚖️ 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 change it (c) we keep it the same
19. 19.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) the paper ate it (c) it turned into air (d) dry juice is see-through
20. 20.True or false: putting the iron away is a job a child can do. (a) True (b) False
21. 21.True or false: cutting the lemon is a job a child can do. (a) True (b) False
22. 22.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) putting the iron away (d) dipping the cotton bud
23. 23.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
24. 24.⚖️ 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
25. 25.⚖️ 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 same paper (d) the ironing time
26. 26.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) lemon juice (d) turmeric powder
28. 28.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) blue words (c) a rainbow (d) dark brown words
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) a small bowl (d) a battery cell
30. 30.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
31. 31.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
32. 32.True or false: reading the message is a job a child can do. (a) True (b) False
33. 33.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
34. 34.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) white paper (c) a small bowl (d) a mirror
35. 35.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
36. 36.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
37. 37.True or false: yeast is needed for the secret lemon message. (a) False (b) True
38. 38.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
39. 39.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a mirror (c) a cotton bud (d) yeast
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) white paper (c) a small bowl (d) turmeric powder

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