Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 814 · 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 balloon (b) a cotton bud (c) a magnet (d) a battery cell
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the same paper (c) the kind of juice (d) how dark the writing is
3. 3.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing turns green (d) writing stays faint
4. 4.⚖️ 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
5. 5.⚖️ 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
6. 6.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
8. 8.🍋 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) putting the iron away
9. 9.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
10. 10.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, in the dark (c) yes, if shaken (d) yes, if cooled
11. 11.⚖️ 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
12. 12.🔮 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
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) an adult with an iron (c) a battery cell (d) a cotton bud
14. 14.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) lemon juice (c) a cotton bud (d) white paper
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) turmeric powder (d) an adult with an iron
17. 17.True or false: plugging in the iron is a job a child can do. (a) False (b) True
18. 18.True or false: writing the message is a job for an adult. (a) False (b) True
19. 19.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
20. 20.🍋 Which of these steps is a job for an adult? (a) reading the message (b) ironing the paper (c) dipping the cotton bud (d) letting the paper dry
21. 21.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a mirror (c) lemon juice (d) an adult with an iron
23. 23.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
24. 24.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) a mirror (d) an adult with an iron
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) how dark the writing is (c) the kind of juice
26. 26.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
27. 27.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
28. 28.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) letting the paper dry (d) plugging in the iron
29. 29.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
30. 30.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
31. 31.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) the youngest child (d) only an adult
32. 32.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) wash your hands (c) lick your fingers (d) rub your eyes
33. 33.🔍 Which is the odd one out? (a) cutting the lemon (b) reading the message (c) putting the iron away (d) ironing the paper
34. 34.🍋 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
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 is needed for the secret lemon message? (a) a balloon (b) lemon juice (c) yeast (d) a battery cell
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the same paper (c) the kind of juice
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.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
40. 40.True or false: yeast is not needed for the secret lemon message. (a) True (b) False

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