Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 201 · 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.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is sticky (c) it is cold (d) it is magnetic
2. 2.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if cooled (c) yes, if shaken (d) yes, in the dark
3. 3.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) almost nothing (d) dark brown words
4. 4.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
5. 5.⚖️ 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 measure it (c) we keep it the same
6. 6.⚖️ 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 cotton bud (c) the same paper (d) the kind of juice
7. 7.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
8. 8.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) letting the paper dry (d) cutting the lemon
9. 9.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) plugging in the iron (d) letting the paper dry
10. 10.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) dipping the cotton bud
11. 11.🔮 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
12. 12.True or false: ironing the paper is a job for an adult. (a) True (b) False
13. 13.🛟 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
14. 14.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a balloon (c) a cotton bud (d) a small bowl
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we measure it (c) we keep it the same
16. 16.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) reading the message (d) putting the iron away
17. 17.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we change it (c) we keep it the same
19. 19.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
20. 20.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
21. 21.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
22. 22.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
23. 23.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
24. 24.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) lemon juice (c) an adult with an iron (d) a cotton bud
25. 25.⚖️ 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
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) a cotton bud (c) an adult with an iron (d) lemon juice
27. 27.🔍 Which is the odd one out? (a) letting the paper dry (b) ironing the paper (c) dipping the cotton bud (d) writing the message
28. 28.🍋 Which of these steps is a job a child can do? (a) writing the message (b) putting the iron away (c) cutting the lemon (d) plugging in the iron
29. 29.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
30. 30.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a battery cell (c) a cotton bud (d) a magnet
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) an adult with an iron (d) a small bowl
32. 32.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) a mirror (c) a battery cell (d) turmeric powder
33. 33.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) dipping the cotton bud (d) putting the iron away
34. 34.⚖️ 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) the ironing time (c) the iron setting (d) the same cotton bud
35. 35.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
36. 36.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) putting the iron away (c) writing the message (d) reading the message
37. 37.True or false: plugging in the iron is a job for an adult. (a) False (b) True
38. 38.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
39. 39.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
40. 40.True or false: letting the paper dry is a job for an adult. (a) True (b) False

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