Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 181 · 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.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) an adult with an iron (c) a battery cell (d) turmeric powder
2. 2.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) rub your eyes (c) lick your fingers (d) wash your hands
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) lemon juice (c) an adult with an iron (d) a cotton bud
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) True (b) False
5. 5.🔍 Which is the odd one out? (a) plugging in the iron (b) ironing the paper (c) dipping the cotton bud (d) cutting the lemon
6. 6.True or false: ironing the paper is a job for an adult. (a) True (b) False
7. 7.True or false: reading the message is a job a child can do. (a) False (b) True
8. 8.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
9. 9.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) turmeric powder (c) a magnet (d) a mirror
10. 10.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
11. 11.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the ironing time
13. 13.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
14. 14.⚖️ 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
15. 15.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
16. 16.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) heat adds colour (d) the juice scorches first
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the iron setting
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) turmeric powder (c) a cotton bud (d) an adult with an iron
19. 19.⚖️ 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) how dark the writing is (c) the ironing time (d) the kind of juice
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a magnet (c) lemon juice (d) white paper
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
22. 22.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) a battery cell (d) an adult with an iron
24. 24.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) almost nothing (c) dark brown words (d) a rainbow
25. 25.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) putting the iron away (d) dipping the cotton bud
26. 26.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) writing stays faint (d) the paper floats
27. 27.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) lemon juice (c) an adult with an iron (d) turmeric powder
28. 28.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
29. 29.⚖️ 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
30. 30.🔍 Which is the odd one out? (a) cutting the lemon (b) letting the paper dry (c) writing the message (d) reading the message
31. 31.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
32. 32.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) writing the message (d) putting the iron away
33. 33.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
34. 34.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is sticky (c) it can burn skin (d) it is cold
35. 35.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) yes, if cooled (d) no, it stays brown
36. 36.⚖️ 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
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we change it (c) we measure it
38. 38.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) dry juice is see-through (d) the paper ate it
39. 39.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True

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