Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 197 · 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.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) only an adult (d) the youngest child
2. 2.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
3. 3.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) letting the paper dry (d) cutting the lemon
4. 4.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) lick your fingers (d) wash your hands
5. 5.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) a small bowl (c) an adult with an iron (d) a cotton bud
6. 6.🔍 Which is the odd one out? (a) writing the message (b) cutting the lemon (c) ironing the paper (d) plugging in the iron
7. 7.🔮 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
8. 8.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
9. 9.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) chemical (d) musical
10. 10.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) green (c) white (d) blue
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the ironing time (c) how dark the writing is
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) lemon juice (d) a magnet
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
14. 14.🔍 Which is the odd one out? (a) ironing the paper (b) reading the message (c) dipping the cotton bud (d) letting the paper dry
15. 15.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) a small bowl (c) an adult with an iron (d) a cotton bud
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) a mirror (d) white paper
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we change it (c) we keep it the same
18. 18.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) how dark the writing is (c) the kind of juice
20. 20.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
21. 21.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
22. 22.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
23. 23.🍋 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
24. 24.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) reading the message (d) plugging in the iron
25. 25.True or false: ironing the paper is a job for an adult. (a) True (b) False
26. 26.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
27. 27.True or false: writing the message is a job a child can do. (a) False (b) True
28. 28.True or false: reading 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 balloon (b) lemon juice (c) a battery cell (d) turmeric powder
30. 30.🍋 Which of these steps is a job for an adult? (a) writing the message (b) putting the iron away (c) reading the message (d) dipping the cotton bud
31. 31.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is sticky (c) it is cold (d) it can burn skin
32. 32.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) turmeric powder (c) a cotton bud (d) an adult with an iron
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the kind of juice (c) the same paper (d) how dark the writing is
35. 35.🔍 Which is the odd one out? (a) plugging in the iron (b) letting the paper dry (c) ironing the paper (d) cutting the lemon
36. 36.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) a mirror (d) turmeric powder
37. 37.True or false: yeast is needed for the secret lemon message. (a) True (b) False
38. 38.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) white paper (d) a battery cell
39. 39.🔮 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
40. 40.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed

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