Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 585 · 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: a mirror is needed for the secret lemon message. (a) False (b) True
2. 2.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) a mirror (d) an adult with an iron
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) turmeric powder (c) an adult with an iron (d) lemon juice
4. 4.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
5. 5.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
6. 6.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) letting the paper dry (d) putting the iron away
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we change it (c) we keep it the same
8. 8.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a battery cell (c) lemon juice (d) a small bowl
9. 9.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) whoever is fastest (c) any child (d) the youngest child
10. 10.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the kind of juice (c) the same cotton bud (d) the ironing time
12. 12.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
13. 13.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
14. 14.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) dipping the cotton bud (c) reading the message (d) letting the paper dry
15. 15.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if shaken (d) yes, if cooled
16. 16.True or false: putting the iron away is a job a child can do. (a) False (b) True
17. 17.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) True (b) False
19. 19.⚖️ 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 keep it the same (c) we change it
20. 20.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) almost nothing (c) blue words (d) dark brown words
21. 21.🔍 Which is the odd one out? (a) reading the message (b) plugging in the iron (c) ironing the paper (d) putting the iron away
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) lemon juice (c) a small bowl (d) an adult with an iron
23. 23.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it can burn skin (d) it is cold
24. 24.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a small bowl (c) yeast (d) lemon juice
25. 25.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) green (c) blue (d) brown
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) an adult with an iron (c) white paper (d) a small bowl
27. 27.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the same paper (c) the iron setting (d) the kind of juice
29. 29.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
30. 30.🧺 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 battery cell (d) a cotton bud
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a mirror (c) a small bowl (d) a cotton bud
33. 33.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) the paper floats (c) it gets darker (d) writing turns green
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) how dark the writing is (c) the kind of juice
35. 35.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
36. 36.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) heat adds colour (d) the juice scorches first
37. 37.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
38. 38.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a magnet (c) an adult with an iron (d) turmeric powder
39. 39.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) chemical (c) physical (d) magnetic
40. 40.True or false: putting the iron away is a job for an adult. (a) True (b) False

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