Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 185 · 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 of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) a balloon (d) lemon juice
2. 2.True or false: plugging in the iron is a job a child can do. (a) False (b) True
3. 3.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
4. 4.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
5. 5.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) yes, if cooled (d) no, it stays brown
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a magnet (c) lemon juice (d) an adult with an iron
7. 7.True or false: cutting the lemon is a job a child can do. (a) False (b) True
8. 8.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it is magnetic (d) it can burn skin
9. 9.True or false: plugging in the iron is a job for an adult. (a) False (b) True
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) lemon juice (d) a balloon
11. 11.🔍 Which is the odd one out? (a) writing the message (b) letting the paper dry (c) ironing the paper (d) reading the message
12. 12.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) almost nothing (c) blue words (d) dark brown words
13. 13.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) it gets darker (d) writing stays faint
14. 14.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
15. 15.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) writing the message (c) letting the paper dry (d) reading the message
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) the kind of juice (c) how dark the writing is (d) the ironing time
17. 17.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) it turned into air (d) dry juice is see-through
18. 18.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) turmeric powder (c) a small bowl (d) a cotton bud
20. 20.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) plugging in the iron (d) dipping the cotton bud
21. 21.True or false: letting the paper dry is a job for an adult. (a) True (b) False
22. 22.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) dipping the cotton bud (d) plugging in the iron
23. 23.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) turmeric powder (c) a balloon (d) yeast
24. 24.🍋 Which of these steps is a job for an adult? (a) reading the message (b) cutting the lemon (c) dipping the cotton bud (d) letting the paper dry
25. 25.True or false: putting the iron away is a job a child can do. (a) False (b) True
26. 26.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) an adult with an iron (d) a battery cell
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) an adult with an iron (c) a small bowl (d) lemon juice
29. 29.🍋 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) reading the message
30. 30.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) dipping the cotton bud (c) reading the message (d) letting the paper dry
31. 31.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
32. 32.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
33. 33.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
34. 34.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
35. 35.⚖️ 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 kind of juice (c) the iron setting (d) the ironing time
36. 36.True or false: reading the message is a job a child can do. (a) True (b) False
37. 37.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) reading the message (d) cutting the lemon
38. 38.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
39. 39.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
40. 40.⚖️ 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

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