Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 938 · 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 keep it the same (b) we change it (c) we measure it
2. 2.True or false: white paper is needed for the secret lemon message. (a) True (b) False
3. 3.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
4. 4.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) plugging in the iron (d) letting the paper dry
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) False (b) True
6. 6.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) dipping the cotton bud (d) ironing the paper
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) a cotton bud (c) white paper (d) lemon juice
8. 8.⚖️ 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
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) white paper (c) a small bowl (d) a cotton bud
10. 10.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) yeast (d) white paper
11. 11.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
12. 12.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
13. 13.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) ironing the paper (d) writing the message
14. 14.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) no, it stays brown (d) yes, if cooled
15. 15.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) yeast (c) a balloon (d) white paper
16. 16.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) the paper floats (d) writing stays faint
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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a magnet (c) a small bowl (d) an adult with an iron
19. 19.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
20. 20.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) skip washing (d) wash your hands
21. 21.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
22. 22.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) whoever is fastest (d) any child
23. 23.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is sticky (d) it is magnetic
24. 24.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
25. 25.🔍 Which is the odd one out? (a) letting the paper dry (b) putting the iron away (c) reading the message (d) writing the message
26. 26.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a mirror (c) a magnet (d) a small bowl
27. 27.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a magnet (c) lemon juice (d) a balloon
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we change it (c) we measure it
29. 29.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) white paper (c) an adult with an iron (d) lemon juice
31. 31.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
32. 32.True or false: letting the paper dry is a job for an adult. (a) False (b) True
33. 33.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
34. 34.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) ironing the paper (d) dipping the cotton bud
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we change it (c) we keep it the same
36. 36.True or false: plugging in the iron is a job for an adult. (a) False (b) True
37. 37.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
38. 38.True or false: ironing the paper is a job a child can do. (a) True (b) False
39. 39.🧺 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) white paper
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True

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