Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 562 · 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 kind of juice”? (a) we change it (b) we measure it (c) we keep it the same
2. 2.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
3. 3.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) plugging in the iron (d) writing the message
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) white paper (d) a balloon
5. 5.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, if cooled (c) yes, in the dark (d) no, it stays brown
6. 6.True or false: letting the paper dry is a job a child can do. (a) False (b) True
7. 7.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) physical (d) chemical
8. 8.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
9. 9.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) cutting the lemon (d) dipping the cotton bud
10. 10.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a magnet (c) a balloon (d) a small bowl
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
12. 12.True or false: putting the iron away is a job for an adult. (a) False (b) True
13. 13.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) yeast (c) lemon juice (d) a cotton bud
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) yeast (c) lemon juice (d) white paper
15. 15.⚖️ 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 same paper (d) the iron setting
16. 16.⚖️ 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
17. 17.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) whoever is fastest (d) only an adult
18. 18.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
19. 19.⚖️ 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 iron setting (c) the ironing time (d) the kind of juice
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False
21. 21.🔍 Which is the odd one out? (a) letting the paper dry (b) ironing the paper (c) plugging in the iron (d) cutting the lemon
22. 22.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a battery cell (c) a small bowl (d) an adult with an iron
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) True (b) False
25. 25.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
26. 26.🔍 Which is the odd one out? (a) reading the message (b) ironing the paper (c) dipping the cotton bud (d) letting the paper dry
27. 27.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) yeast (c) a cotton bud (d) turmeric powder
28. 28.🧺 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) a cotton bud (d) lemon juice
29. 29.True or false: plugging in the iron is a job for an adult. (a) False (b) True
30. 30.True or false: writing the message is a job for an adult. (a) True (b) False
31. 31.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) dry juice is see-through (c) the ink is magnetic (d) the paper ate it
32. 32.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
33. 33.🔮 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
34. 34.⚖️ 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) the ironing time (c) how dark the writing is
35. 35.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) almost nothing (d) a rainbow
36. 36.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
37. 37.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) the kind of juice (c) how dark the writing is
39. 39.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) wash your hands (d) rub your eyes
40. 40.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) ironing the paper (d) reading the message

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