Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 236 · 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 — ironing the paper? (a) an adult does it (b) a child can do it
2. 2.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
3. 3.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a cotton bud (c) a mirror (d) an adult with an iron
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we keep it the same (c) we change it
6. 6.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a mirror (c) a magnet (d) white paper
7. 7.⚖️ 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 keep it the same (c) we measure it
8. 8.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) the juice scorches first (c) heat adds colour (d) paper turns lemony
9. 9.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
10. 10.🧺 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) a cotton bud
11. 11.⚖️ 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 cotton bud (c) how dark the writing is (d) the ironing time
12. 12.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we measure it (c) we change it
14. 14.True or false: reading the message is a job a child can do. (a) False (b) True
15. 15.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) the youngest child (d) any child
16. 16.True or false: white paper is needed for the secret lemon message. (a) False (b) True
17. 17.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) green (c) white (d) blue
18. 18.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
19. 19.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
20. 20.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) wash your hands (d) rub your eyes
21. 21.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) a small bowl (d) turmeric powder
22. 22.⚖️ 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
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) an adult with an iron (d) yeast
24. 24.🍋 Which of these steps is a job a child can do? (a) reading the message (b) ironing the paper (c) plugging in the iron (d) cutting the lemon
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
26. 26.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
27. 27.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
28. 28.True or false: plugging in the iron is a job a child can do. (a) False (b) True
29. 29.🔍 Which is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) plugging in the iron (d) ironing the paper
30. 30.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) a balloon (d) white paper
32. 32.🔍 Which is the odd one out? (a) letting the paper dry (b) plugging in the iron (c) dipping the cotton bud (d) reading the message
33. 33.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is magnetic (c) it is sticky (d) it can burn skin
34. 34.⚖️ 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 measure it (c) we change it
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a mirror (c) a small bowl (d) a cotton bud
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
37. 37.🔍 Which is the odd one out? (a) writing the message (b) plugging in the iron (c) putting the iron away (d) ironing the paper
38. 38.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) almost nothing (d) blue words
39. 39.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
40. 40.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) writing the message (d) plugging in the iron

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