Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 783 · 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.True or false: white paper is needed for the secret lemon message. (a) True (b) False
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
3. 3.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
4. 4.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
5. 5.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) plugging in the iron (d) reading the message
6. 6.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
7. 7.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
8. 8.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
9. 9.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) lemon juice (c) turmeric powder (d) a magnet
10. 10.True or false: putting the iron away is a job a child can do. (a) False (b) True
11. 11.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
12. 12.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
13. 13.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) plugging in the iron (c) writing the message (d) reading the message
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) the kind of juice (c) the same paper (d) the ironing time
15. 15.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) brown (c) blue (d) green
16. 16.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing turns green (d) writing stays faint
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) a mirror (d) lemon juice
18. 18.⚖️ 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
19. 19.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
20. 20.True or false: letting the paper dry is a job a child can do. (a) False (b) True
21. 21.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) an adult with an iron (c) yeast (d) turmeric powder
22. 22.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it is sticky (d) it can burn skin
23. 23.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
24. 24.True or false: ironing the paper is a job for an adult. (a) True (b) False
25. 25.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) white paper (c) a battery cell (d) a mirror
26. 26.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) dry juice is see-through (d) the paper ate it
27. 27.⚖️ 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
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) white paper (d) a magnet
29. 29.⚖️ 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 keep it the same (c) we measure it
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) True (b) False
31. 31.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) dipping the cotton bud (c) ironing the paper (d) plugging in the iron
32. 32.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
33. 33.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) a cotton bud (d) a balloon
34. 34.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
35. 35.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
37. 37.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
38. 38.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) letting the paper dry (c) writing the message (d) dipping the cotton bud
39. 39.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) rub your eyes (c) lick your fingers (d) wash your hands
40. 40.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) physical (c) magnetic (d) chemical

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