Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 203 · 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.True or false: plugging in the iron is a job for an adult. (a) False (b) True
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the same paper (c) how dark the writing is (d) the ironing time
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) the same cotton bud (c) the kind of juice (d) the same paper
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a balloon (c) white paper (d) an adult with an iron
5. 5.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) musical (c) magnetic (d) physical
6. 6.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) turmeric powder (c) a balloon (d) lemon juice
7. 7.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we measure it (c) we change it
9. 9.🛟 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
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) white paper (d) a magnet
11. 11.True or false: writing the message is a job for an adult. (a) True (b) False
12. 12.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) the kind of juice (c) how dark the writing is
14. 14.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) the youngest child (d) any child
15. 15.True or false: putting the iron away is a job a child can do. (a) False (b) True
16. 16.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
17. 17.🧺 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
18. 18.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
19. 19.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) putting the iron away (d) writing the message
20. 20.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
21. 21.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
22. 22.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing stays faint (c) writing turns green (d) the paper floats
23. 23.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
24. 24.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) reading the message (d) cutting the lemon
25. 25.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) putting the iron away (c) writing the message (d) reading the message
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) True (b) False
27. 27.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) almost nothing (d) dark brown words
28. 28.🔍 Which is the odd one out? (a) letting the paper dry (b) cutting the lemon (c) reading the message (d) writing the message
29. 29.🍋 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
30. 30.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) writing the message (c) reading the message (d) dipping the cotton bud
31. 31.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
32. 32.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) reading the message (d) putting the iron away
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we change it (c) we keep it the same
34. 34.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
35. 35.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it is cold (d) it can burn skin
36. 36.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
37. 37.True or false: yeast is needed for the secret lemon message. (a) True (b) False
38. 38.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
39. 39.⚖️ 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
40. 40.True or false: yeast is not needed for the secret lemon message. (a) True (b) False

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