Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 164 · 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.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) musical (c) chemical (d) magnetic
2. 2.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a magnet (c) yeast (d) a mirror
3. 3.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a battery cell (c) yeast (d) a mirror
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we measure it (c) we change it
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we keep it the same (c) we measure it
6. 6.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) cutting the lemon (d) dipping the cotton bud
7. 7.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) an adult with an iron (c) lemon juice (d) a battery cell
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) white paper (c) lemon juice (d) a cotton bud
9. 9.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the same cotton bud (c) the same paper (d) the iron setting
11. 11.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) writing stays faint (d) it gets darker
12. 12.⚖️ 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
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) yeast (c) an adult with an iron (d) white paper
14. 14.⚖️ 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) True (b) False
15. 15.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
16. 16.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, in the dark (c) yes, if cooled (d) yes, if shaken
17. 17.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
18. 18.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
19. 19.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) skip washing (d) wash your hands
20. 20.🔍 Which is the odd one out? (a) plugging in the iron (b) letting the paper dry (c) cutting the lemon (d) ironing the paper
21. 21.True or false: letting the paper dry is a job a child can do. (a) False (b) True
22. 22.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a magnet (c) lemon juice (d) a cotton bud
24. 24.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) turmeric powder (c) white paper (d) a cotton bud
25. 25.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) almost nothing (c) dark brown words (d) a rainbow
26. 26.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
27. 27.⚖️ 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 same paper (c) the kind of juice
28. 28.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a mirror (c) a small bowl (d) turmeric powder
29. 29.True or false: cutting the lemon is a job a child can do. (a) False (b) True
30. 30.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is magnetic (c) it is cold (d) it is sticky
31. 31.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) turmeric powder (c) an adult with an iron (d) a mirror
32. 32.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) False (b) True
34. 34.🍋 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) cutting the lemon
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a battery cell (d) a small bowl
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we measure it (c) we change it
37. 37.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
38. 38.⚖️ 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 ironing time (d) the same paper
39. 39.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) white paper (d) a magnet

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