Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 202 · 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 needed for the secret lemon message? (a) a cotton bud (b) a mirror (c) a magnet (d) yeast
2. 2.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
3. 3.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) putting the iron away (d) letting the paper dry
4. 4.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) the paper floats (d) writing stays faint
5. 5.⚖️ 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
6. 6.⚖️ 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
7. 7.True or false: plugging in the iron is a job a child can do. (a) True (b) False
8. 8.True or false: ironing the paper is a job a child can do. (a) False (b) True
9. 9.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
10. 10.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) wash your hands (d) lick your fingers
11. 11.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) dark brown words (c) blue words (d) almost nothing
12. 12.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
13. 13.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) white paper (d) a balloon
15. 15.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
17. 17.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
18. 18.True or false: writing the message is a job for an adult. (a) True (b) False
19. 19.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) any child (d) only an adult
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) True (b) False
21. 21.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
22. 22.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
23. 23.⚖️ 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
24. 24.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
25. 25.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
26. 26.True or false: putting the iron away is a job a child can do. (a) False (b) True
27. 27.True or false: letting the paper dry is a job a child can do. (a) False (b) True
28. 28.True or false: ironing the paper is a job for an adult. (a) False (b) True
29. 29.⚖️ 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 change it (c) we measure it
30. 30.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) how dark the writing is (c) the iron setting (d) the kind of juice
32. 32.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) cutting the lemon (c) plugging in the iron (d) dipping the cotton bud
33. 33.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
34. 34.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) white paper (c) an adult with an iron (d) yeast
35. 35.⚖️ 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
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we change it (c) we keep it the same
37. 37.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
38. 38.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) no, it stays brown (d) yes, if shaken
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) white paper (c) a cotton bud (d) an adult with an iron
40. 40.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) ironing the paper (d) letting the paper dry

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