Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 914 · 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? Which of these is kept the same? (a) how dark the writing is (b) the ironing time (c) the kind of juice
2. 2.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) putting the iron away (d) dipping the cotton bud
3. 3.True or false: reading the message is a job a child can do. (a) False (b) True
4. 4.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) writing the message (c) plugging in the iron (d) cutting the lemon
5. 5.True or false: yeast is needed for the secret lemon message. (a) True (b) False
6. 6.⚖️ 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
7. 7.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) dipping the cotton bud (d) ironing the paper
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
9. 9.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) only an adult (d) whoever is fastest
10. 10.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
11. 11.🔮 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
12. 12.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) lemon juice (d) a small bowl
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 magnet (d) lemon juice
14. 14.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
15. 15.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
16. 16.True or false: letting the paper dry is a job a child can do. (a) True (b) False
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we measure it (c) we change it
18. 18.True or false: cutting the lemon is a job for an adult. (a) True (b) False
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the iron setting (c) the ironing time (d) the same paper
20. 20.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) wash your hands (c) skip washing (d) rub your eyes
21. 21.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
22. 22.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
23. 23.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) an adult with an iron (c) yeast (d) a magnet
24. 24.⚖️ 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
25. 25.🔍 Which is the odd one out? (a) putting the iron away (b) letting the paper dry (c) ironing the paper (d) cutting the lemon
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) an adult with an iron (d) a mirror
27. 27.True or false: reading the message is a job for an adult. (a) True (b) False
28. 28.🧺 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) white paper (d) yeast
29. 29.🍋 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
30. 30.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) lemon juice (d) yeast
31. 31.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
33. 33.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
34. 34.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) an adult with an iron (c) a cotton bud (d) a small bowl
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) a cotton bud (d) turmeric powder
37. 37.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) plugging in the iron (d) writing the message
38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a battery cell (c) white paper (d) an adult with an iron
39. 39.True or false: ironing the paper is a job for an adult. (a) True (b) False
40. 40.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False

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