Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 59 · 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.⚖️ 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 measure it (c) we change it
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) yeast (d) lemon juice
3. 3.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
4. 4.True or false: writing the message is a job for an adult. (a) True (b) False
5. 5.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) lemon juice (d) an adult with an iron
6. 6.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) dry juice is see-through (d) the ink is magnetic
7. 7.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) wash your hands (c) rub your eyes (d) skip washing
8. 8.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
9. 9.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a balloon (d) lemon juice
11. 11.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
12. 12.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
13. 13.True or false: reading the message is a job for an adult. (a) False (b) True
14. 14.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) the ironing time (c) how dark the writing is (d) the kind of juice
16. 16.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) yes, in the dark (d) no, it stays brown
17. 17.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) dark brown words (c) blue words (d) almost nothing
18. 18.⚖️ 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
19. 19.⚖️ 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
20. 20.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing stays faint (c) it gets darker (d) writing turns green
21. 21.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) letting the paper dry (c) dipping the cotton bud (d) reading the message
22. 22.⚖️ 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
23. 23.🔍 Which is the odd one out? (a) writing the message (b) ironing the paper (c) plugging in the iron (d) putting the iron away
24. 24.⚖️ 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) how dark the writing is (c) the kind of juice (d) the iron setting
25. 25.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
26. 26.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) a mirror (d) a cotton bud
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we change it (c) we keep it the same
28. 28.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) reading the message (c) cutting the lemon (d) ironing the paper
29. 29.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
30. 30.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
31. 31.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
32. 32.🔍 Which is the odd one out? (a) plugging in the iron (b) dipping the cotton bud (c) cutting the lemon (d) ironing the paper
33. 33.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) cutting the lemon (d) dipping the cotton bud
34. 34.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) letting the paper dry (d) putting the iron away
35. 35.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
36. 36.🧺 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) turmeric powder
37. 37.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) putting the iron away (d) writing the message
38. 38.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) lemon juice (c) a mirror (d) a balloon
39. 39.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
40. 40.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) dipping the cotton bud (d) ironing the paper

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