Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 580 · 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 iron setting”? (a) we measure it (b) we keep it the same (c) we change it
2. 2.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a magnet (c) a balloon (d) white paper
3. 3.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
4. 4.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the iron is brown (c) the juice scorches first (d) heat adds colour
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we measure it (c) we keep it the same
6. 6.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
7. 7.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) dipping the cotton bud (d) cutting the lemon
8. 8.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) rub your eyes (d) wash your hands
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the same cotton bud
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a mirror (c) white paper (d) lemon juice
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) turmeric powder (d) lemon juice
12. 12.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
13. 13.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) putting the iron away
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) yeast (d) an adult with an iron
16. 16.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
17. 17.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) blue (c) green (d) white
18. 18.⚖️ 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 ironing time (c) the iron setting (d) the same cotton bud
19. 19.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) cutting the lemon (d) reading the message
20. 20.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) physical (c) magnetic (d) musical
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
22. 22.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if cooled (c) yes, if shaken (d) yes, in the dark
23. 23.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we keep it the same (c) we measure it
25. 25.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
26. 26.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) a magnet (d) lemon juice
28. 28.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) whoever is fastest (d) the youngest child
29. 29.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a mirror (c) a magnet (d) a balloon
30. 30.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) the paper ate it (d) dry juice is see-through
31. 31.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
32. 32.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a mirror (c) white paper (d) a cotton bud
33. 33.⚖️ 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
34. 34.True or false: plugging in the iron is a job for an adult. (a) True (b) False
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) True (b) False
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) white paper (c) lemon juice (d) a cotton bud
37. 37.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) reading the message (d) plugging in the iron
38. 38.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) writing stays faint (d) the paper floats
39. 39.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) dipping the cotton bud (c) ironing the paper (d) putting the iron away
40. 40.True or false: cutting the lemon is a job a child can do. (a) False (b) True

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