Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 549 · 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 does the lemon writing turn brown with heat? (a) paper turns lemony (b) the iron is brown (c) the juice scorches first (d) heat adds colour
2. 2.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it can burn skin (c) it is sticky (d) it is cold
3. 3.⚖️ 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) False (b) True
4. 4.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
5. 5.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) turmeric powder (c) an adult with an iron (d) a battery cell
6. 6.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
7. 7.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
8. 8.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a battery cell (c) a cotton bud (d) a magnet
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) a magnet (d) a small bowl
10. 10.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) almost nothing (c) a rainbow (d) blue words
11. 11.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) the youngest child (d) whoever is fastest
12. 12.🧺 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) white paper (d) a mirror
13. 13.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) a battery cell (d) white paper
14. 14.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
15. 15.True or false: letting the paper dry is a job a child can do. (a) False (b) True
16. 16.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we measure it (c) we keep it the same
18. 18.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) brown (d) white
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 kind of juice (d) the iron setting
20. 20.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) writing the message (c) cutting the lemon (d) plugging in the iron
21. 21.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
22. 22.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) writing stays faint (d) the paper floats
23. 23.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) writing the message (d) plugging in the iron
24. 24.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) writing the message (d) plugging in the iron
25. 25.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) wash your hands (d) lick your fingers
26. 26.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a small bowl (c) a mirror (d) an adult with an iron
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same cotton bud (b) the kind of juice (c) how dark the writing is
28. 28.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a battery cell (d) an adult with an iron
30. 30.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
31. 31.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
32. 32.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
33. 33.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) cutting the lemon (d) dipping the cotton bud
34. 34.🔍 Which is the odd one out? (a) dipping the cotton bud (b) cutting the lemon (c) plugging in the iron (d) ironing the paper
35. 35.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) no, it stays brown (d) yes, in the dark
36. 36.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
37. 37.True or false: reading the message is a job for an adult. (a) False (b) True
38. 38.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) a small bowl (d) white paper
39. 39.⚖️ 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 keep it the same (c) we measure it
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True

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