Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 865 · 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: putting the iron away is a job for an adult. (a) True (b) False
2. 2.True or false: dipping the cotton bud is a job a child can do. (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) a battery cell (d) white paper
4. 4.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
5. 5.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is sticky (d) it is magnetic
6. 6.⚖️ 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 change it (c) we measure it
7. 7.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) putting the iron away (d) dipping the cotton bud
8. 8.⚖️ 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
9. 9.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) yeast (c) a battery cell (d) a cotton bud
10. 10.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
11. 11.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
12. 12.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) turmeric powder (c) white paper (d) a cotton bud
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we change it (c) we measure it
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) the iron setting (c) how dark the writing is (d) the kind of juice
16. 16.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
17. 17.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
19. 19.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
20. 20.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) chemical (c) musical (d) magnetic
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) yeast (d) an adult with an iron
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a magnet (c) lemon juice (d) white paper
23. 23.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) only an adult (d) the youngest child
24. 24.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) it turned into air (d) dry juice is see-through
25. 25.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
26. 26.⚖️ 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 kind of juice (c) the same paper (d) how dark the writing is
27. 27.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) almost nothing (c) dark brown words (d) blue words
28. 28.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) plugging in the iron (d) dipping the cotton bud
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a balloon (c) lemon juice (d) a small bowl
30. 30.True or false: plugging in the iron is a job a child can do. (a) True (b) False
31. 31.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
32. 32.🔍 Which is the odd one out? (a) ironing the paper (b) dipping the cotton bud (c) reading the message (d) letting the paper dry
33. 33.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a balloon (c) a small bowl (d) a cotton bud
34. 34.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, if cooled (c) no, it stays brown (d) yes, in the dark
35. 35.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
36. 36.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
37. 37.True or false: cutting the lemon is a job for an adult. (a) True (b) False
38. 38.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) turmeric powder (c) a magnet (d) an adult with an iron
39. 39.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
40. 40.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it

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