Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 956 · 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 ironing time”? (a) we change it (b) we measure it (c) we keep it the same
2. 2.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
3. 3.⚖️ 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 ironing time (d) the iron setting
4. 4.⚖️ 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
5. 5.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) a small bowl (c) lemon juice (d) an adult with an iron
6. 6.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a balloon (c) lemon juice (d) turmeric powder
7. 7.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if cooled (c) yes, if shaken (d) no, it stays brown
8. 8.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
9. 9.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) cutting the lemon (d) writing the message
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we measure it (c) we keep it the same
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
12. 12.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we measure it (c) we keep it the same
14. 14.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
15. 15.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a balloon (c) an adult with an iron (d) turmeric powder
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 battery cell is not needed for the secret lemon message. (a) False (b) True
18. 18.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) letting the paper dry (d) cutting the lemon
19. 19.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
20. 20.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) a cotton bud (d) a battery cell
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a battery cell (d) a cotton bud
22. 22.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) cutting the lemon (d) dipping the cotton bud
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) False (b) True
24. 24.🔍 Which is the odd one out? (a) putting the iron away (b) reading the message (c) ironing the paper (d) cutting the lemon
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a small bowl (c) white paper (d) a balloon
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the same cotton bud (c) the kind of juice (d) the same paper
27. 27.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) a rainbow (d) almost nothing
28. 28.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
29. 29.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is sticky (c) it can burn skin (d) it is cold
30. 30.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the ironing time (c) how dark the writing is
32. 32.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) ironing the paper (d) dipping the cotton bud
33. 33.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) dipping the cotton bud (c) writing the message (d) letting the paper dry
34. 34.True or false: white paper is needed for the secret lemon message. (a) False (b) True
35. 35.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
36. 36.True or false: reading the message is a job a child can do. (a) True (b) False
37. 37.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) skip washing (c) lick your fingers (d) rub your eyes
38. 38.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
39. 39.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
40. 40.True or false: ironing the paper is a job a child can do. (a) True (b) False

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