Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 161 · 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.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
2. 2.🔍 Which is the odd one out? (a) putting the iron away (b) writing the message (c) letting the paper dry (d) dipping the cotton bud
3. 3.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
4. 4.True or false: yeast is needed for the secret lemon message. (a) False (b) True
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a battery cell (d) a small bowl
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 paper (b) the same cotton bud (c) the kind of juice (d) the ironing time
7. 7.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) only an adult (d) whoever is fastest
8. 8.🍋 Which of these steps is a job for an adult? (a) writing the message (b) plugging in the iron (c) letting the paper dry (d) reading the message
9. 9.True or false: ironing the paper is a job a child can do. (a) False (b) True
10. 10.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) a battery cell (d) white paper
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the iron setting (c) how dark the writing is (d) the ironing time
12. 12.🔍 Which is the odd one out? (a) cutting the lemon (b) writing the message (c) letting the paper dry (d) dipping the cotton bud
13. 13.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) dark brown words (d) almost nothing
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we change it (c) we measure it
15. 15.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) writing the message (c) plugging in the iron (d) cutting the lemon
16. 16.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) a cotton bud (d) a balloon
18. 18.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, in the dark (d) yes, if cooled
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) turmeric powder (d) white paper
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) an adult with an iron (d) yeast
21. 21.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a mirror (c) lemon juice (d) an adult with an iron
23. 23.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) writing the message (d) cutting the lemon
24. 24.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
25. 25.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
27. 27.⚖️ 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
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we measure it (c) we keep it the same
29. 29.True or false: reading the message is a job a child can do. (a) False (b) True
30. 30.🍋 Secret message: who does this step — plugging in the iron? (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? What do we do with “the same paper”? (a) we keep it the same (b) we change it (c) we measure it
32. 32.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) ironing the paper (c) plugging in the iron (d) putting the iron away
33. 33.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
34. 34.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
35. 35.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
36. 36.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
37. 37.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a battery cell (c) a mirror (d) an adult with an iron
38. 38.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the iron is brown (c) heat adds colour (d) the juice scorches first
39. 39.⚖️ 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
40. 40.True or false: letting the paper dry is a job for an adult. (a) False (b) True

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