Invisible Ink Experiment Worksheet

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

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