Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 652 · 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.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) dry juice is see-through (d) the ink is magnetic
2. 2.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) cutting the lemon (d) dipping the cotton bud
3. 3.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
4. 4.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
5. 5.True or false: ironing the paper is a job a child can do. (a) True (b) False
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we measure it (c) we keep it the same
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) a cotton bud (d) a battery cell
8. 8.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) writing the message (d) ironing the paper
9. 9.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) wash your hands (d) lick your fingers
10. 10.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
11. 11.⚖️ 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
12. 12.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
13. 13.⚖️ 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
14. 14.⚖️ 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
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) how dark the writing is (c) the kind of juice
16. 16.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
17. 17.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
18. 18.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
19. 19.True or false: writing the message is a job for an adult. (a) True (b) False
20. 20.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) turmeric powder (d) white paper
21. 21.True or false: letting the paper dry is a job for an adult. (a) True (b) False
22. 22.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
23. 23.True or false: white paper is needed for the secret lemon message. (a) True (b) False
24. 24.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) dark brown words (d) almost nothing
25. 25.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
26. 26.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
27. 27.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) plugging in the iron
28. 28.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
29. 29.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) cutting the lemon (c) writing the message (d) dipping the cotton bud
30. 30.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it can burn skin (c) it is cold (d) it is sticky
31. 31.⚖️ 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
32. 32.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the ironing time (c) the kind of juice
34. 34.🔍 Which is the odd one out? (a) plugging in the iron (b) letting the paper dry (c) putting the iron away (d) ironing the paper
35. 35.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
36. 36.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
37. 37.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) turmeric powder (c) yeast (d) a cotton bud
38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) lemon juice (d) a balloon
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) a cotton bud (d) a mirror
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) turmeric powder (c) lemon juice (d) a small bowl

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