Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 341 · 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.⚖️ 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
2. 2.🧺 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 balloon
3. 3.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) True (b) False
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) lemon juice (c) a small bowl (d) white paper
6. 6.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) how dark the writing is (c) the ironing time (d) the iron setting
8. 8.🍋 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
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
10. 10.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
11. 11.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is magnetic (d) it is sticky
12. 12.⚖️ 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) how dark the writing is (c) the same paper (d) the iron setting
13. 13.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a mirror (c) a small bowl (d) lemon juice
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we change it (c) we keep it the same
16. 16.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) writing the message (d) cutting the lemon
17. 17.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
18. 18.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a balloon (c) a battery cell (d) a cotton bud
19. 19.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
20. 20.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a magnet (c) yeast (d) white paper
21. 21.True or false: white paper is needed for the secret lemon message. (a) True (b) False
22. 22.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
23. 23.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) plugging in the iron (c) writing the message (d) dipping the cotton bud
24. 24.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
25. 25.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) yeast (c) a mirror (d) an adult with an iron
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
27. 27.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) green (c) white (d) blue
28. 28.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) ironing the paper (d) dipping the cotton bud
29. 29.True or false: letting the paper dry is a job a child can do. (a) False (b) True
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we change it (c) we measure it
31. 31.True or false: cutting the lemon is a job a child can do. (a) True (b) False
32. 32.True or false: a mirror is 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 kept the same. (a) False (b) True
34. 34.⚖️ 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
35. 35.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
36. 36.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
37. 37.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
38. 38.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
39. 39.True or false: ironing the paper is a job for an adult. (a) False (b) True
40. 40.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) reading the message (d) cutting the lemon

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