Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 819 · 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 of these is needed for the secret lemon message? (a) turmeric powder (b) a battery cell (c) a cotton bud (d) a magnet
2. 2.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing stays faint (c) writing turns green (d) the paper floats
3. 3.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
4. 4.⚖️ 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 measure it (c) we keep it the same
5. 5.⚖️ 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 kind of juice (c) the ironing time (d) how dark the writing is
6. 6.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) letting the paper dry (d) plugging in the iron
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) a battery cell (d) a cotton bud
8. 8.🧺 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) yeast (d) lemon juice
9. 9.True or false: ironing the paper is a job for an adult. (a) False (b) True
10. 10.True or false: reading the message is a job a child can do. (a) False (b) True
11. 11.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) putting the iron away (d) writing the message
12. 12.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the ink is magnetic (c) the paper ate it (d) it turned into air
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we measure it (c) we change it
14. 14.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) white (d) brown
15. 15.🛟 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
16. 16.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
17. 17.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
18. 18.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
19. 19.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) white paper (c) a cotton bud (d) an adult with an iron
21. 21.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
22. 22.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
23. 23.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) physical (c) magnetic (d) chemical
24. 24.True or false: cutting the lemon is a job for an adult. (a) True (b) False
25. 25.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
26. 26.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
27. 27.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) only an adult (d) whoever is fastest
28. 28.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) dipping the cotton bud (d) cutting the lemon
29. 29.🔍 Which is the odd one out? (a) letting the paper dry (b) cutting the lemon (c) dipping the cotton bud (d) writing the message
30. 30.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) almost nothing (c) a rainbow (d) blue words
31. 31.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
32. 32.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) a cotton bud (c) white paper (d) an adult with an iron
33. 33.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) lemon juice (c) an adult with an iron (d) a cotton bud
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
35. 35.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
36. 36.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
37. 37.⚖️ 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
38. 38.⚖️ 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) True (b) False
39. 39.⚖️ 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 measure it (c) we change it
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) an adult with an iron (c) a small bowl (d) turmeric powder

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