Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 195 · 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 is the odd one out? (a) cutting the lemon (b) dipping the cotton bud (c) letting the paper dry (d) writing the message
2. 2.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
3. 3.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) dry juice is see-through (d) it turned into air
4. 4.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
5. 5.🍋 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) dipping the cotton bud
6. 6.True or false: letting the paper dry is a job a child can do. (a) True (b) False
7. 7.True or false: reading the message is a job for an adult. (a) True (b) False
8. 8.True or false: yeast is needed for the secret lemon message. (a) True (b) False
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) the kind of juice (c) the ironing time (d) how dark the writing is
10. 10.🔮 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
11. 11.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) an adult with an iron (c) yeast (d) a cotton bud
12. 12.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) white paper (c) lemon juice (d) turmeric powder
13. 13.⚖️ 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
14. 14.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) lemon juice (c) a battery cell (d) a balloon
15. 15.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) False (b) True
17. 17.True or false: putting the iron away is a job a child can do. (a) False (b) True
18. 18.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is magnetic (c) it is cold (d) it is sticky
19. 19.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) plugging in the iron (d) writing the message
20. 20.⚖️ 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 same paper
21. 21.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) blue words (d) almost nothing
22. 22.⚖️ 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 keep it the same (c) we change it
23. 23.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
24. 24.🧺 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 battery cell
25. 25.⚖️ 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) how dark the writing is (d) the ironing time
26. 26.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
27. 27.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) chemical (c) magnetic (d) musical
28. 28.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a balloon (c) a magnet (d) a mirror
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) False (b) True
30. 30.⚖️ 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
31. 31.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
32. 32.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) wash your hands (d) rub your eyes
33. 33.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
35. 35.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a cotton bud (d) a magnet
37. 37.True or false: plugging in the iron is a job a child can do. (a) True (b) False
38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) turmeric powder (d) an adult with an iron
39. 39.⚖️ 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 measure it (c) we change it
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a balloon (c) lemon juice (d) a small bowl

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