Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 467 · 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 keep it the same (c) we measure it
2. 2.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
3. 3.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) yeast (c) a battery cell (d) a balloon
4. 4.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) lemon juice (c) a magnet (d) a cotton bud
5. 5.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) dipping the cotton bud (d) putting the iron away
6. 6.⚖️ 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
7. 7.True or false: putting the iron away is a job a child can do. (a) True (b) False
8. 8.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
9. 9.⚖️ 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
10. 10.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) an adult with an iron (c) a battery cell (d) lemon juice
11. 11.🛟 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
12. 12.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is sticky (c) it is cold (d) it can burn skin
13. 13.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
14. 14.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) writing stays faint (d) the paper floats
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we keep it the same (c) we measure it
16. 16.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
17. 17.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) the youngest child (d) only an adult
18. 18.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) dry juice is see-through (c) it turned into air (d) the paper ate it
19. 19.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) a cotton bud (c) lemon juice (d) an adult with an iron
21. 21.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
22. 22.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) a cotton bud (c) lemon juice (d) a small bowl
23. 23.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
24. 24.True or false: reading the message is a job for an adult. (a) True (b) False
25. 25.⚖️ 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
26. 26.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) writing the message (d) cutting the lemon
27. 27.⚖️ 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 same paper (c) the same cotton bud (d) the ironing time
28. 28.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
29. 29.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) lemon juice (c) a cotton bud (d) turmeric powder
30. 30.🍋 Which of these steps is a job for an adult? (a) writing the message (b) reading the message (c) plugging in the iron (d) dipping the cotton bud
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
32. 32.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we measure it (c) we change it
34. 34.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
35. 35.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) cutting the lemon (c) plugging in the iron (d) ironing the paper
36. 36.True or false: writing the message is a job a child can do. (a) False (b) True
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) a small bowl (c) an adult with an iron (d) lemon juice
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
39. 39.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we measure it (c) we change it

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