Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 707 · 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.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) dipping the cotton bud (d) plugging in the iron
2. 2.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
3. 3.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a mirror (c) a balloon (d) white paper
4. 4.⚖️ 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
5. 5.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
6. 6.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) plugging in the iron (d) writing the message
7. 7.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the juice scorches first (c) paper turns lemony (d) the iron is brown
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a battery cell (c) lemon juice (d) a small bowl
9. 9.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) chemical (d) musical
10. 10.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
11. 11.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
12. 12.🍋 Which of these steps is a job for an adult? (a) writing the message (b) reading the message (c) dipping the cotton bud (d) putting the iron away
13. 13.🍋 Which of these steps is a job for an adult? (a) writing the message (b) reading the message (c) dipping the cotton bud (d) ironing the paper
14. 14.⚖️ 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) how dark the writing is (c) the same cotton bud (d) the kind of juice
15. 15.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) writing the message (d) putting the iron away
16. 16.🛟 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
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) True (b) False
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) how dark the writing is (c) the kind of juice
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) yeast (c) a small bowl (d) white paper
20. 20.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
21. 21.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
22. 22.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) almost nothing (d) blue words
23. 23.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
24. 24.🔍 Which is the odd one out? (a) putting the iron away (b) writing the message (c) letting the paper dry (d) reading the message
25. 25.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
26. 26.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) a battery cell (d) a small bowl
27. 27.🔍 Which is the odd one out? (a) ironing the paper (b) letting the paper dry (c) writing the message (d) reading the message
28. 28.True or false: plugging in the iron is a job for an adult. (a) True (b) False
29. 29.⚖️ 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
30. 30.⚖️ 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
31. 31.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
32. 32.🍋 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
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) an adult with an iron (c) white paper (d) a small bowl
34. 34.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) no, it stays brown (c) yes, if shaken (d) yes, in the dark
35. 35.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
36. 36.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
37. 37.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
38. 38.🧺 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) turmeric powder (d) white paper
39. 39.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) white paper (d) a balloon
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) a magnet (d) white paper

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