Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 88 · 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: plugging in the iron 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? What do we do with “the iron setting”? (a) we measure it (b) we change it (c) we keep it the same
3. 3.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
4. 4.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a mirror (d) an adult with an iron
6. 6.🍋 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
7. 7.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) a magnet (d) white paper
9. 9.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
10. 10.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) any child (d) whoever is fastest
11. 11.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
12. 12.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) reading the message (c) plugging in the iron (d) cutting the lemon
13. 13.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) blue words (d) almost nothing
14. 14.🧺 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) lemon juice
15. 15.⚖️ 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 change it (c) we measure it
16. 16.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
17. 17.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
18. 18.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a mirror (c) a small bowl (d) yeast
19. 19.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
20. 20.True or false: plugging in the iron is a job for an adult. (a) True (b) False
21. 21.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is magnetic (d) it is cold
22. 22.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) dipping the cotton bud (c) plugging in the iron (d) ironing the paper
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the iron setting (c) how dark the writing is (d) the same paper
24. 24.True or false: ironing the paper is a job for an adult. (a) True (b) False
25. 25.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) letting the paper dry (d) cutting the lemon
26. 26.🔍 Which is the odd one out? (a) plugging in the iron (b) writing the message (c) ironing the paper (d) putting the iron away
27. 27.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
28. 28.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
29. 29.🔍 Which is the odd one out? (a) reading the message (b) plugging in the iron (c) letting the paper dry (d) writing the message
30. 30.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the ink is magnetic (c) dry juice is see-through (d) the paper ate it
31. 31.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) green (c) blue (d) brown
32. 32.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) white paper (c) a magnet (d) lemon juice
33. 33.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
34. 34.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) wash your hands (c) skip washing (d) rub your eyes
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) False (b) True
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) a battery cell (d) white paper
37. 37.True or false: writing the message is a job a child can do. (a) True (b) False
38. 38.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
39. 39.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) chemical (d) musical
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) False (b) True

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