Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 719 · 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 small bowl (b) a cotton bud (c) a mirror (d) white paper
2. 2.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
3. 3.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
4. 4.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it is cold (d) it can burn skin
5. 5.🧺 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) white paper (d) turmeric powder
6. 6.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if cooled (c) no, it stays brown (d) yes, if shaken
7. 7.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) turmeric powder (c) a balloon (d) a mirror
8. 8.🍋 Which of these steps is a job for an adult? (a) writing the message (b) cutting the lemon (c) reading the message (d) letting the paper dry
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a balloon (c) white paper (d) a cotton bud
10. 10.⚖️ 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 kind of juice (c) the same cotton bud
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
12. 12.🔍 Which is the odd one out? (a) letting the paper dry (b) ironing the paper (c) dipping the cotton bud (d) writing the message
13. 13.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
14. 14.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) brown (c) green (d) white
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) how dark the writing is (c) the iron setting (d) the kind of juice
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) a magnet (d) white paper
17. 17.🛟 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
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) a mirror (d) a small bowl
19. 19.⚖️ 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
20. 20.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) dipping the cotton bud (d) plugging in the iron
21. 21.True or false: ironing the paper is a job a child can do. (a) False (b) True
22. 22.🔍 Which is the odd one out? (a) plugging in the iron (b) ironing the paper (c) letting the paper dry (d) putting the iron away
23. 23.⚖️ 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
24. 24.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) paper turns lemony (c) heat adds colour (d) the iron is brown
25. 25.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) the ink is magnetic (d) dry juice is see-through
26. 26.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) letting the paper dry (d) cutting the lemon
27. 27.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
28. 28.⚖️ 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
29. 29.⚖️ 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 keep it the same (c) we change it
30. 30.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
31. 31.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
32. 32.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
33. 33.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
34. 34.⚖️ 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 iron setting (d) the same cotton bud
35. 35.⚖️ 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
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a battery cell (c) a small bowl (d) an adult with an iron
37. 37.⚖️ 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
38. 38.⚖️ 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 change it (c) we measure it
39. 39.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) cutting the lemon (c) reading the message (d) plugging in the iron
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) a small bowl (d) a magnet

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