Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 107 · 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 the one thing we change? (a) the same cotton bud (b) the ironing time (c) the kind of juice (d) the iron setting
2. 2.⚖️ 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
3. 3.True or false: cutting the lemon is a job for an adult. (a) False (b) True
4. 4.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
5. 5.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
6. 6.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is magnetic (c) it is cold (d) it is sticky
7. 7.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
8. 8.⚖️ 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) True (b) False
9. 9.True or false: cutting the lemon is a job a child can do. (a) True (b) False
10. 10.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) lemon juice (d) yeast
12. 12.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) yeast (d) white paper
13. 13.⚖️ 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 iron setting (c) the kind of juice (d) how dark the writing is
14. 14.True or false: putting the iron away is a job for an adult. (a) True (b) False
15. 15.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
16. 16.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) writing the message (d) cutting the lemon
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) True (b) False
19. 19.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) whoever is fastest (d) only an adult
20. 20.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
21. 21.True or false: letting the paper dry is a job a child can do. (a) False (b) True
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) an adult with an iron (c) white paper (d) lemon juice
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) how dark the writing is (c) the kind of juice
24. 24.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
25. 25.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the paper ate it (c) it turned into air (d) the ink is magnetic
26. 26.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) plugging in the iron (d) dipping the cotton bud
27. 27.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) lick your fingers (c) skip washing (d) rub your eyes
28. 28.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) an adult with an iron (c) white paper (d) turmeric powder
29. 29.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a balloon (d) a cotton bud
31. 31.⚖️ 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
32. 32.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a magnet (c) an adult with an iron (d) a mirror
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we change it (c) we keep it the same
34. 34.True or false: putting the iron away is a job a child can do. (a) True (b) False
35. 35.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
36. 36.🔍 Which is the odd one out? (a) cutting the lemon (b) letting the paper dry (c) writing the message (d) reading the message
37. 37.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) cutting the lemon (d) dipping the cotton bud
38. 38.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we measure it (c) we keep it the same
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) an adult with an iron (d) lemon juice

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