Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 698 · 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 steps is a job a child can do? (a) dipping the cotton bud (b) cutting the lemon (c) putting the iron away (d) ironing the paper
2. 2.True or false: cutting the lemon is a job a child can do. (a) False (b) True
3. 3.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) only an adult (d) the youngest child
4. 4.True or false: reading the message is a job a child can do. (a) False (b) True
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we change it (c) we keep it the same
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) a small bowl (c) white paper (d) lemon juice
7. 7.⚖️ 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 iron setting
8. 8.True or false: putting the iron away is a job a child can do. (a) True (b) False
9. 9.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
10. 10.⚖️ 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 same cotton bud (c) how dark the writing is (d) the ironing time
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) an adult with an iron (c) a small bowl (d) lemon juice
12. 12.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
13. 13.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) yeast (c) a mirror (d) a magnet
14. 14.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
15. 15.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) putting the iron away (d) reading the message
16. 16.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
17. 17.🔮 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
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a cotton bud (d) turmeric powder
19. 19.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) brown (c) white (d) blue
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we measure it (c) we change it
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) an adult with an iron (c) a cotton bud (d) a small bowl
22. 22.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a balloon (c) a magnet (d) white paper
23. 23.True or false: putting the iron away is a job for an adult. (a) False (b) True
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
25. 25.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) writing the message (d) ironing the paper
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) a cotton bud (c) white paper (d) lemon juice
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) lemon juice (d) a battery cell
28. 28.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) the ink is magnetic (d) dry juice is see-through
29. 29.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) dipping the cotton bud (c) writing the message (d) letting the paper dry
30. 30.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) an adult with an iron (c) a battery cell (d) lemon juice
32. 32.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) chemical (c) physical (d) magnetic
33. 33.⚖️ 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
34. 34.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
35. 35.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) letting the paper dry (d) plugging in the iron
36. 36.🍋 Secret message: who does this step — plugging in the iron? (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 kind of juice is the one thing we change. (a) False (b) True
38. 38.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) reading the message (d) plugging in the iron
39. 39.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
40. 40.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it

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