Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 379 · 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.⚖️ 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
2. 2.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) white paper (c) an adult with an iron (d) a magnet
3. 3.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) physical (d) chemical
4. 4.True or false: putting the iron away is a job a child can do. (a) True (b) False
5. 5.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
6. 6.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is sticky (c) it can burn skin (d) it is cold
7. 7.🔮 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
8. 8.🔍 Which is the odd one out? (a) letting the paper dry (b) reading the message (c) plugging in the iron (d) dipping the cotton bud
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) the same paper (c) the iron setting (d) how dark the writing is
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) a small bowl (c) lemon juice (d) a cotton bud
11. 11.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) putting the iron away (d) dipping the cotton bud
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a balloon (c) a cotton bud (d) turmeric powder
13. 13.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
14. 14.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) ironing the paper (d) reading the message
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 ironing time (b) the same paper (c) the kind of juice (d) the iron setting
16. 16.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) an adult with an iron (c) a balloon (d) white paper
18. 18.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
19. 19.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) cutting the lemon (d) reading the message
20. 20.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) the ink is magnetic (d) dry juice is see-through
21. 21.True or false: ironing the paper is a job a child can do. (a) False (b) True
22. 22.⚖️ 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) False (b) True
23. 23.True or false: writing the message is a job a child can do. (a) False (b) True
24. 24.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
25. 25.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) skip washing (c) lick your fingers (d) rub your eyes
26. 26.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) white (c) green (d) brown
27. 27.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) heat adds colour (d) the juice scorches first
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) yeast (c) a small bowl (d) lemon juice
29. 29.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) the youngest child (d) only an adult
30. 30.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) yes, if cooled (d) no, it stays brown
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a cotton bud (c) lemon juice (d) yeast
32. 32.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
33. 33.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
34. 34.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) a balloon (c) a mirror (d) a magnet
35. 35.True or false: ironing the paper is a job for an adult. (a) True (b) False
36. 36.⚖️ 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
37. 37.⚖️ 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 measure it (c) we change it
38. 38.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
39. 39.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a mirror (c) a balloon (d) an adult with an iron
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) an adult with an iron (c) a small bowl (d) white paper

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