Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 537 · 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 cotton bud (b) a small bowl (c) a balloon (d) an adult with an iron
2. 2.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) an adult with an iron (d) turmeric powder
3. 3.⚖️ 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
4. 4.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
5. 5.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
7. 7.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
8. 8.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we measure it (c) we change it
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) the same paper (c) the kind of juice (d) how dark the writing is
11. 11.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
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 ironing time (b) the same paper (c) the kind of juice (d) the iron setting
13. 13.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
14. 14.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
15. 15.🛟 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
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) a mirror (d) a cotton bud
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
18. 18.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
19. 19.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) the juice scorches first (c) paper turns lemony (d) heat adds colour
20. 20.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
21. 21.🍋 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
22. 22.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) only an adult (d) whoever is fastest
23. 23.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
24. 24.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) a cotton bud (d) yeast
26. 26.True or false: ironing the paper is a job a child can do. (a) False (b) True
27. 27.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
28. 28.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) writing the message (c) dipping the cotton bud (d) reading the message
29. 29.⚖️ 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
30. 30.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
31. 31.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) a battery cell (d) a cotton bud
32. 32.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
33. 33.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
34. 34.True or false: putting the iron away is a job a child can do. (a) False (b) True
35. 35.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) cutting the lemon (c) plugging in the iron (d) reading the message
36. 36.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) rub your eyes (d) wash your hands
37. 37.True or false: plugging in the iron is a job for an adult. (a) True (b) False
38. 38.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) reading the message (d) putting the iron away
39. 39.True or false: ironing the paper is a job for an adult. (a) False (b) True
40. 40.⚖️ 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

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