Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 595 · 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: letting the paper dry is a job for an adult. (a) True (b) False
2. 2.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
3. 3.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) dipping the cotton bud (d) cutting the lemon
4. 4.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a mirror (c) yeast (d) white paper
5. 5.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the same paper (c) the iron setting (d) the kind of juice
7. 7.⚖️ 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 same paper (c) how dark the writing is (d) the same cotton bud
8. 8.🛟 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
9. 9.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) magnetic (c) physical (d) musical
10. 10.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) dipping the cotton bud (c) cutting the lemon (d) plugging in the iron
11. 11.True or false: plugging in the iron is a job for an adult. (a) False (b) True
12. 12.🧺 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) white paper (d) yeast
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) an adult with an iron (d) a battery cell
14. 14.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
15. 15.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) the ink is magnetic (d) dry juice is see-through
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) lemon juice (d) a mirror
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) the kind of juice (c) how dark the writing is
18. 18.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
19. 19.🔍 Which is the odd one out? (a) cutting the lemon (b) writing the message (c) putting the iron away (d) ironing the paper
20. 20.True or false: plugging in the iron is a job a child can do. (a) False (b) True
21. 21.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
22. 22.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
23. 23.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) plugging in the iron (d) writing the message
24. 24.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a magnet (c) a cotton bud (d) an adult with an iron
25. 25.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
26. 26.True or false: putting the iron away is a job a child can do. (a) True (b) False
27. 27.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
28. 28.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) putting the iron away (d) writing the message
29. 29.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
30. 30.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) False (b) True
32. 32.⚖️ 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) how dark the writing is (c) the ironing time
33. 33.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) white (c) blue (d) green
34. 34.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) dipping the cotton bud (d) cutting the lemon
35. 35.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) turmeric powder (d) lemon juice
37. 37.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) any child (d) only an adult
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) False (b) True
39. 39.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
40. 40.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) reading the message (c) letting the paper dry (d) writing the message

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