Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 574 · 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? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the ironing time
2. 2.🔮 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
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the kind of juice (c) the ironing time (d) how dark the writing is
4. 4.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) a magnet (d) an adult with an iron
5. 5.⚖️ 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 same cotton bud (c) the ironing time (d) the same paper
6. 6.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) plugging in the iron (c) dipping the cotton bud (d) reading the message
7. 7.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
8. 8.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) letting the paper dry (d) writing the message
9. 9.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) lemon juice (d) a balloon
11. 11.⚖️ 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) True (b) False
12. 12.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) cutting the lemon (c) dipping the cotton bud (d) writing the message
13. 13.True or false: letting the paper dry is a job for an adult. (a) False (b) True
14. 14.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
15. 15.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
16. 16.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
17. 17.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) yeast (c) a small bowl (d) a magnet
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 change it (b) we measure it (c) we keep it the same
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
20. 20.🔮 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
21. 21.⚖️ 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
22. 22.⚖️ 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 keep it the same (c) we change it
23. 23.⚖️ 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
24. 24.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
25. 25.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
26. 26.True or false: yeast is needed for the secret lemon message. (a) True (b) False
27. 27.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a battery cell (c) lemon juice (d) yeast
28. 28.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we change it (c) we measure it
30. 30.🔍 Which is the odd one out? (a) writing the message (b) putting the iron away (c) letting the paper dry (d) dipping the cotton bud
31. 31.🔍 Which is the odd one out? (a) reading the message (b) ironing the paper (c) writing the message (d) dipping the cotton bud
32. 32.⚖️ 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
33. 33.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) lick your fingers (c) skip washing (d) rub your eyes
34. 34.⚖️ 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
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
36. 36.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) cutting the lemon (d) letting the paper dry
37. 37.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) physical (c) magnetic (d) chemical
38. 38.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a mirror (c) an adult with an iron (d) a cotton bud
40. 40.True or false: cutting the lemon is a job a child can do. (a) False (b) True

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