Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 353 · 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.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) paper turns lemony (c) heat adds colour (d) the iron is brown
2. 2.True or false: ironing the paper is a job for an adult. (a) True (b) False
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we measure it (c) we keep it the same
4. 4.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
5. 5.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a small bowl (c) lemon juice (d) a mirror
6. 6.🔍 Which is the odd one out? (a) letting the paper dry (b) cutting the lemon (c) writing the message (d) dipping the cotton bud
7. 7.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, in the dark (c) yes, if shaken (d) yes, if cooled
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) a magnet (d) a cotton bud
9. 9.🧺 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) white paper
10. 10.⚖️ 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 kind of juice (c) the ironing time (d) the same paper
11. 11.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a cotton bud (c) yeast (d) turmeric powder
12. 12.⚖️ 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 kind of juice (c) the same cotton bud
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
14. 14.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
15. 15.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) the paper floats (d) writing stays faint
16. 16.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a magnet (c) a battery cell (d) white paper
17. 17.🔍 Which is the odd one out? (a) dipping the cotton bud (b) ironing the paper (c) writing the message (d) letting the paper dry
18. 18.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a mirror (c) a magnet (d) an adult with an iron
19. 19.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) wash your hands (d) lick your fingers
20. 20.True or false: putting the iron away is a job a child can do. (a) False (b) True
21. 21.True or false: cutting the lemon is a job for an adult. (a) False (b) True
22. 22.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
23. 23.🔍 Which is the odd one out? (a) putting the iron away (b) dipping the cotton bud (c) ironing the paper (d) plugging in the iron
24. 24.🛟 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
25. 25.True or false: writing the message is a job a child can do. (a) False (b) True
26. 26.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) reading the message (d) ironing the paper
27. 27.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) the kind of juice (c) the same cotton bud (d) how dark the writing is
29. 29.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we keep it the same (c) we change it
31. 31.⚖️ 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 same paper (c) the kind of juice
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) yeast (d) an adult with an iron
33. 33.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) blue (c) green (d) white
34. 34.⚖️ 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 change it (c) we measure it
35. 35.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) almost nothing (d) dark brown words
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
37. 37.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) cutting the lemon (d) letting the paper dry
38. 38.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) cutting the lemon (c) plugging in the iron (d) ironing the paper
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 — letting the paper dry? (a) a child can do it (b) an adult does it

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