Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 630 · 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.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
2. 2.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
3. 3.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
4. 4.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) cutting the lemon (d) writing the message
5. 5.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a mirror (c) a small bowl (d) white paper
6. 6.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) dipping the cotton bud (d) putting the iron away
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) an adult with an iron (d) a battery cell
8. 8.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) an adult with an iron (c) yeast (d) white paper
9. 9.🔍 Which is the odd one out? (a) cutting the lemon (b) letting the paper dry (c) ironing the paper (d) putting the iron away
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the same cotton bud (c) how dark the writing is (d) the ironing time
11. 11.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) reading the message (d) ironing the paper
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) a cotton bud (d) yeast
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) True (b) False
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) False (b) True
15. 15.True or false: letting the paper dry is a job for an adult. (a) True (b) False
16. 16.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
17. 17.True or false: plugging in the iron is a job for an adult. (a) False (b) True
18. 18.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we keep it the same (c) we change it
20. 20.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
21. 21.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) yes, in the dark (d) no, it stays brown
22. 22.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
23. 23.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a battery cell (c) yeast (d) a mirror
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
25. 25.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) reading the message (d) plugging in the iron
26. 26.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) blue words (c) dark brown words (d) a rainbow
27. 27.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) letting the paper dry (d) putting the iron away
28. 28.⚖️ 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) how dark the writing is (c) the same paper (d) the same cotton bud
29. 29.True or false: ironing the paper is a job for an adult. (a) False (b) True
30. 30.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) the ink is magnetic (d) dry juice is see-through
31. 31.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
32. 32.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) the youngest child (d) only an adult
33. 33.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
34. 34.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) ironing the paper (c) reading the message (d) writing the message
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a magnet (c) white paper (d) lemon juice
36. 36.🍋 Which of these steps is a job a child can do? (a) writing the message (b) plugging in the iron (c) putting the iron away (d) ironing the paper
37. 37.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
38. 38.🔍 Which is the odd one out? (a) cutting the lemon (b) dipping the cotton bud (c) writing the message (d) reading the message
39. 39.⚖️ 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 change it (c) we measure it
40. 40.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed

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