Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 355 · 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 not needed for the secret lemon message? (a) a small bowl (b) white paper (c) a battery cell (d) lemon juice
2. 2.⚖️ 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 change it (c) we measure it
3. 3.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing stays faint (d) writing turns green
4. 4.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
5. 5.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) reading the message (d) putting the iron away
6. 6.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
7. 7.⚖️ 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 ironing time (c) the same cotton bud (d) how dark the writing is
8. 8.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) a rainbow (c) dark brown words (d) blue words
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
10. 10.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) white (c) brown (d) green
11. 11.🛟 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
12. 12.🧺 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 balloon (d) a small bowl
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we keep it the same (c) we change it
14. 14.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) putting the iron away (d) dipping the cotton bud
15. 15.⚖️ 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
16. 16.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) the youngest child (d) any child
17. 17.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) yeast (c) white paper (d) a cotton bud
19. 19.🍋 Which of these steps is a job for an adult? (a) reading the message (b) ironing the paper (c) dipping the cotton bud (d) writing the message
20. 20.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
22. 22.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
23. 23.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
24. 24.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it is magnetic (d) it can burn skin
25. 25.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
26. 26.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
27. 27.True or false: yeast is needed for the secret lemon message. (a) True (b) False
28. 28.True or false: writing the message is a job for an adult. (a) False (b) True
29. 29.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a mirror (c) yeast (d) an adult with an iron
30. 30.True or false: putting the iron away is a job for an adult. (a) False (b) True
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a magnet (c) white paper (d) lemon juice
32. 32.True or false: reading the message is a job for an adult. (a) True (b) False
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.🔍 Which is the odd one out? (a) dipping the cotton bud (b) ironing the paper (c) plugging in the iron (d) putting the iron away
35. 35.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
36. 36.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
37. 37.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) chemical (c) musical (d) physical
38. 38.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) lemon juice (c) a magnet (d) turmeric powder
39. 39.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
40. 40.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed

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