Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 906 · 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.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) the kind of juice (c) how dark the writing is (d) the same cotton bud
3. 3.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
4. 4.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) the juice scorches first (d) heat adds colour
5. 5.🍋 Which of these steps is a job for an adult? (a) writing the message (b) cutting the lemon (c) reading the message (d) dipping the cotton bud
6. 6.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a battery cell (c) a mirror (d) a small bowl
7. 7.🔍 Which is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) letting the paper dry (d) reading the message
8. 8.True or false: yeast is needed for the secret lemon message. (a) False (b) True
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) a magnet (d) white paper
10. 10.⚖️ 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 change it (c) we measure it
11. 11.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) putting the iron away (d) dipping the cotton bud
12. 12.🧺 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) turmeric powder (d) white paper
13. 13.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) a small bowl (c) an adult with an iron (d) white paper
14. 14.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) writing turns green (c) the paper floats (d) it gets darker
15. 15.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) putting the iron away (d) dipping the cotton bud
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the iron setting (c) the kind of juice (d) the same cotton bud
17. 17.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) dipping the cotton bud (d) cutting the lemon
18. 18.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) yes, if cooled (d) no, it stays brown
19. 19.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
20. 20.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) a rainbow (d) almost nothing
21. 21.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
22. 22.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) reading the message (d) writing the message
23. 23.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
24. 24.True or false: cutting the lemon is a job a child can do. (a) False (b) True
25. 25.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is sticky (c) it is magnetic (d) it can burn skin
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) lemon juice (c) a cotton bud (d) white paper
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same cotton bud (b) how dark the writing is (c) the kind of juice
28. 28.⚖️ 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
29. 29.True or false: writing the message is a job for an adult. (a) False (b) True
30. 30.True or false: plugging in the iron is a job a child can do. (a) False (b) True
31. 31.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) physical (c) chemical (d) magnetic
32. 32.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a cotton bud (c) yeast (d) turmeric powder
33. 33.🔍 Which is the odd one out? (a) ironing the paper (b) reading the message (c) letting the paper dry (d) dipping the cotton bud
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the ironing time (c) the kind of juice
35. 35.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
36. 36.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) only an adult (d) any child
37. 37.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
38. 38.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) yeast (c) a balloon (d) white paper
39. 39.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
40. 40.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) plugging in the iron (c) dipping the cotton bud (d) reading the message

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