Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 149 · 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 is the odd one out? (a) cutting the lemon (b) putting the iron away (c) ironing the paper (d) letting the paper dry
2. 2.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is magnetic (d) it is cold
3. 3.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
5. 5.True or false: plugging in the iron is a job a child can do. (a) False (b) True
6. 6.🔍 Which is the odd one out? (a) letting the paper dry (b) putting the iron away (c) dipping the cotton bud (d) reading the message
7. 7.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
8. 8.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
9. 9.⚖️ 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 keep it the same (c) we measure it
10. 10.⚖️ 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 same paper (c) how dark the writing is
11. 11.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
12. 12.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) ironing the paper (d) reading the message
13. 13.⚖️ 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) False (b) True
14. 14.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
15. 15.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
16. 16.⚖️ 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) how dark the writing is (c) the same cotton bud
17. 17.⚖️ 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 iron setting (c) the kind of juice
18. 18.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) white paper (c) turmeric powder (d) a magnet
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) a mirror (d) an adult with an iron
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
21. 21.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) lemon juice (c) a small bowl (d) a cotton bud
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we keep it the same (c) we measure it
23. 23.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) lemon juice (c) an adult with an iron (d) a small bowl
24. 24.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
25. 25.🔮 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
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) a balloon (d) an adult with an iron
27. 27.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a mirror (c) a small bowl (d) a magnet
28. 28.⚖️ 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
29. 29.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
30. 30.🔍 Which is the odd one out? (a) plugging in the iron (b) reading the message (c) letting the paper dry (d) dipping the cotton bud
31. 31.⚖️ 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) False (b) True
32. 32.🔍 Which is the odd one out? (a) reading the message (b) ironing the paper (c) letting the paper dry (d) dipping the cotton bud
33. 33.🧺 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 battery cell (d) white paper
34. 34.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
35. 35.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the paper ate it (c) the ink is magnetic (d) it turned into air
36. 36.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
37. 37.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) wash your hands (c) rub your eyes (d) skip washing
38. 38.🛟 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
39. 39.True or false: ironing the paper is a job a child can do. (a) True (b) False
40. 40.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed

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