Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 97 · 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: a cotton bud is needed for the secret lemon message. (a) True (b) False
2. 2.True or false: ironing the paper is a job for an adult. (a) True (b) False
3. 3.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) musical (c) magnetic (d) physical
4. 4.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) an adult with an iron (d) turmeric powder
6. 6.True or false: letting the paper dry is a job for an adult. (a) True (b) False
7. 7.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the same paper (c) how dark the writing is
9. 9.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) letting the paper dry (c) reading the message (d) dipping the cotton bud
10. 10.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the ironing time (c) the same paper (d) the iron setting
12. 12.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
13. 13.True or false: yeast is needed for the secret lemon message. (a) True (b) False
14. 14.⚖️ 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 keep it the same (c) we change it
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.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) almost nothing (c) a rainbow (d) dark brown words
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we change it (c) we measure it
18. 18.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
19. 19.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) letting the paper dry (d) ironing the paper
20. 20.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we keep it the same (c) we measure it
22. 22.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it can burn skin (d) it is cold
23. 23.True or false: ironing the paper is a job a child can do. (a) True (b) False
24. 24.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
25. 25.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) writing the message (d) cutting the lemon
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we change it (c) we measure it
27. 27.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
28. 28.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a balloon (c) a mirror (d) a magnet
29. 29.🔍 Which is the odd one out? (a) reading the message (b) dipping the cotton bud (c) letting the paper dry (d) ironing the paper
30. 30.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) skip washing (d) wash your hands
31. 31.🧺 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) yeast (d) a small bowl
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a mirror (c) lemon juice (d) white paper
33. 33.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a magnet (c) an adult with an iron (d) turmeric powder
34. 34.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
35. 35.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) brown (d) white
36. 36.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) only an adult (d) whoever is fastest
37. 37.⚖️ 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
38. 38.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
39. 39.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
40. 40.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) reading the message (c) plugging in the iron (d) ironing the paper

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