Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 133 · 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 can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) dry juice is see-through (c) the paper ate it (d) it turned into air
2. 2.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) reading the message (d) ironing the paper
3. 3.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
4. 4.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) turmeric powder (c) white paper (d) an adult with an iron
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we change it (c) we measure it
6. 6.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
7. 7.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) wash your hands (c) rub your eyes (d) lick your fingers
8. 8.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is magnetic (c) it is cold (d) it is sticky
9. 9.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
10. 10.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, if cooled (d) yes, in the dark
11. 11.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) reading the message (d) putting the iron away
12. 12.⚖️ 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
13. 13.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) heat adds colour (c) the iron is brown (d) paper turns lemony
14. 14.⚖️ 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 keep it the same (c) we change it
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a small bowl (d) yeast
16. 16.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
17. 17.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
18. 18.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) cutting the lemon (d) letting the paper dry
19. 19.⚖️ 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
20. 20.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) blue words (c) dark brown words (d) a rainbow
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the same cotton bud (c) the ironing time (d) how dark the writing is
22. 22.🍋 Which of these steps is a job for an adult? (a) reading the message (b) plugging in the iron (c) writing the message (d) letting the paper dry
23. 23.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) any child (c) the youngest child (d) whoever is fastest
24. 24.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) white paper (d) a magnet
25. 25.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) white paper (c) a balloon (d) a mirror
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we keep it the same (c) we measure it
27. 27.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
28. 28.🔍 Which is the odd one out? (a) writing the message (b) cutting the lemon (c) putting the iron away (d) ironing the paper
29. 29.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) writing stays faint (d) it gets darker
30. 30.⚖️ 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
31. 31.⚖️ 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
32. 32.True or false: ironing the paper is a job a child can do. (a) True (b) False
33. 33.⚖️ 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 same paper (c) the iron setting (d) the kind of juice
34. 34.⚖️ 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
35. 35.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) ironing the paper (d) dipping the cotton bud
36. 36.🍋 Which of these steps is a job a child can do? (a) writing the message (b) plugging in the iron (c) putting the iron away (d) ironing the paper
37. 37.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a cotton bud (c) turmeric powder (d) yeast
38. 38.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
39. 39.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
40. 40.True or false: white paper is needed for the secret lemon message. (a) False (b) True

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