Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 446 · 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.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) dry juice is see-through (c) the paper ate it (d) it turned into air
2. 2.True or false: plugging in the iron is a job for an adult. (a) False (b) True
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) an adult with an iron (d) a mirror
4. 4.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) plugging in the iron (d) letting the paper dry
5. 5.⚖️ 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
6. 6.⚖️ 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
7. 7.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) cutting the lemon (d) writing the message
8. 8.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
9. 9.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) any child (d) the youngest child
10. 10.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) how dark the writing is (c) the kind of juice (d) the iron setting
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we measure it (c) we keep it the same
13. 13.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) white paper (d) a mirror
14. 14.True or false: reading the message is a job for an adult. (a) False (b) True
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the kind of juice (c) the ironing time (d) the same cotton bud
16. 16.🍋 Which of these steps is a job a child can do? (a) reading the message (b) cutting the lemon (c) putting the iron away (d) ironing the paper
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we keep it the same (c) we change it
18. 18.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
19. 19.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) writing the message (c) reading the message (d) dipping the cotton bud
20. 20.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) chemical (d) musical
21. 21.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
22. 22.True or false: writing the message is a job a child can do. (a) False (b) True
23. 23.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) yes, if shaken (d) no, it stays brown
24. 24.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a balloon (c) an adult with an iron (d) turmeric powder
25. 25.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a battery cell (c) a cotton bud (d) a balloon
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we change it (c) we keep it the same
27. 27.⚖️ 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
28. 28.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
29. 29.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
30. 30.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) white (c) blue (d) brown
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we change it (c) we keep it the same
32. 32.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
33. 33.True or false: letting the paper dry is a job for an adult. (a) False (b) True
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
35. 35.True or false: reading the message is a job a child can do. (a) False (b) True
36. 36.True or false: white paper is needed for the secret lemon message. (a) True (b) False
37. 37.🔍 Which is the odd one out? (a) plugging in the iron (b) writing the message (c) reading the message (d) letting the paper dry
38. 38.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
39. 39.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) an adult with an iron (d) turmeric powder
40. 40.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it

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