Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 125 · 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: letting the paper dry is a job a child can do. (a) True (b) False
2. 2.⚖️ 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 same cotton bud (c) the same paper (d) the kind of juice
3. 3.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) blue words (c) dark brown words (d) a rainbow
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a balloon (c) lemon juice (d) a cotton bud
5. 5.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
6. 6.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
7. 7.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
8. 8.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) lemon juice (c) an adult with an iron (d) a mirror
9. 9.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
10. 10.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) turmeric powder (c) a battery cell (d) a magnet
11. 11.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
12. 12.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
13. 13.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) any child (d) only an adult
14. 14.⚖️ 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 measure it (c) we change it
15. 15.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) plugging in the iron (d) writing the message
16. 16.⚖️ 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) False (b) True
17. 17.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) ironing the paper (d) reading the message
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) True (b) False
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) a small bowl (d) a mirror
20. 20.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) no, it stays brown (d) yes, in the dark
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we measure it (c) we change it
22. 22.🔍 Which is the odd one out? (a) reading the message (b) ironing the paper (c) putting the iron away (d) plugging in the iron
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we keep it the same (c) we measure it
24. 24.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
25. 25.⚖️ 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 measure it (c) we change it
26. 26.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) chemical (d) musical
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) the iron setting (c) the same cotton bud (d) how dark the writing is
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) lemon juice (d) turmeric powder
29. 29.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
30. 30.True or false: letting the paper dry is a job for an adult. (a) True (b) False
31. 31.🍋 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
32. 32.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
33. 33.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it is magnetic (d) it can burn skin
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a small bowl (c) lemon juice (d) a battery cell
36. 36.⚖️ 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 change it (c) we keep it the same
37. 37.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
38. 38.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) writing the message (d) plugging in the iron
39. 39.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
40. 40.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) letting the paper dry (c) reading the message (d) dipping the cotton bud

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