Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 488 · 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.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) skip washing (d) wash your hands
2. 2.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
3. 3.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
4. 4.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) plugging in the iron (d) letting the paper dry
5. 5.True or false: cutting the lemon is a job for an adult. (a) False (b) True
6. 6.⚖️ 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
7. 7.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
8. 8.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) a cotton bud (c) white paper (d) a small bowl
9. 9.⚖️ 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
10. 10.⚖️ 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
11. 11.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the juice scorches first (c) paper turns lemony (d) the iron is brown
12. 12.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
13. 13.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
14. 14.True or false: yeast is needed for the secret lemon message. (a) False (b) True
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
16. 16.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, in the dark (d) yes, if cooled
17. 17.⚖️ 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) True (b) False
18. 18.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) almost nothing (c) a rainbow (d) blue words
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we keep it the same (c) we measure it
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the kind of juice (c) the iron setting (d) how dark the writing is
21. 21.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
22. 22.True or false: ironing the paper is a job for an adult. (a) True (b) False
23. 23.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
24. 24.🧺 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 cotton bud (d) a magnet
25. 25.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
26. 26.🍋 Which of these steps is a job a child can do? (a) writing the message (b) cutting the lemon (c) plugging in the iron (d) ironing the paper
27. 27.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) lemon juice (c) turmeric powder (d) a magnet
28. 28.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) dipping the cotton bud (d) putting the iron away
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) the kind of juice (c) how dark the writing is
30. 30.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
31. 31.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) True (b) False
33. 33.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
34. 34.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
35. 35.True or false: plugging in the iron is a job a child can do. (a) True (b) False
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) how dark the writing is (c) the same paper (d) the iron setting
37. 37.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
38. 38.🔮 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
39. 39.⚖️ 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
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a mirror (c) a cotton bud (d) white paper

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