Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 319 · 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.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
2. 2.🔍 Which is the odd one out? (a) cutting the lemon (b) reading the message (c) putting the iron away (d) ironing the paper
3. 3.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) wash your hands (c) lick your fingers (d) skip washing
4. 4.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) it gets darker (d) writing stays faint
5. 5.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
6. 6.🔍 Which is the odd one out? (a) ironing the paper (b) letting the paper dry (c) reading the message (d) writing the message
7. 7.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
8. 8.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) magnetic (c) physical (d) chemical
9. 9.🍋 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) putting the iron away
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) a battery cell (d) an adult with an iron
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) lemon juice (d) a magnet
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) an adult with an iron (d) turmeric powder
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we keep it the same (c) we measure it
14. 14.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) a magnet (d) a small bowl
15. 15.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) writing the message (c) reading the message (d) letting the paper dry
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) an adult with an iron (c) yeast (d) a cotton bud
17. 17.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) almost nothing (c) blue words (d) a rainbow
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the same cotton bud (c) the same paper (d) the kind of juice
19. 19.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
20. 20.⚖️ 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 same paper (d) the same cotton bud
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) lemon juice (c) a small bowl (d) yeast
22. 22.🍋 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
23. 23.🔍 Which is the odd one out? (a) letting the paper dry (b) reading the message (c) dipping the cotton bud (d) cutting the lemon
24. 24.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
25. 25.⚖️ 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
26. 26.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
27. 27.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
28. 28.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) yeast (c) white paper (d) a magnet
29. 29.🧺 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 balloon (d) white paper
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 change it (c) we keep it the same
31. 31.🔮 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
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a mirror (c) an adult with an iron (d) white paper
33. 33.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) yeast (c) lemon juice (d) a battery cell
34. 34.True or false: plugging in the iron is a job a child can do. (a) True (b) False
35. 35.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
36. 36.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
37. 37.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a magnet (c) a balloon (d) an adult with an iron
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
39. 39.🔍 Which is the odd one out? (a) letting the paper dry (b) cutting the lemon (c) putting the iron away (d) ironing the paper
40. 40.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True

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