Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 730 · 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 can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the ink is magnetic (c) the paper ate it (d) it turned into air
2. 2.🔍 Which is the odd one out? (a) putting the iron away (b) letting the paper dry (c) reading the message (d) writing the message
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) lemon juice (d) a magnet
4. 4.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it is magnetic (d) it can burn skin
5. 5.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
6. 6.⚖️ 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
7. 7.True or false: yeast is needed for the secret lemon message. (a) True (b) False
8. 8.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
9. 9.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
10. 10.True or false: putting the iron away is a job for an adult. (a) False (b) True
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) lemon juice (d) a mirror
12. 12.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a balloon (c) white paper (d) a cotton bud
13. 13.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
14. 14.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
15. 15.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) lemon juice (c) a cotton bud (d) white paper
16. 16.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) reading the message (d) ironing the paper
17. 17.🔮 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
18. 18.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) whoever is fastest (c) any child (d) the youngest child
19. 19.🔍 Which is the odd one out? (a) letting the paper dry (b) ironing the paper (c) putting the iron away (d) cutting the lemon
20. 20.⚖️ 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) how dark the writing is
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a battery cell (c) a cotton bud (d) an adult with an iron
22. 22.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) an adult with an iron (c) a magnet (d) a cotton bud
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.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
25. 25.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) letting the paper dry (d) cutting the lemon
26. 26.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) writing the message (d) cutting the lemon
27. 27.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) plugging in the iron (d) reading the message
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) turmeric powder (c) an adult with an iron (d) lemon juice
29. 29.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) white paper (c) a small bowl (d) lemon juice
30. 30.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
31. 31.True or false: letting the paper dry is a job a child can do. (a) False (b) True
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) lemon juice (d) a balloon
33. 33.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) almost nothing (d) dark brown words
34. 34.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) wash your hands (c) skip washing (d) lick your fingers
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (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) a small bowl (c) a cotton bud (d) yeast
37. 37.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
38. 38.True or false: ironing the paper is a job a child can do. (a) False (b) True
39. 39.⚖️ 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) how dark the writing is (c) the same paper (d) the iron setting
40. 40.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) letting the paper dry (d) cutting the lemon

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