Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 180 · 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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) a magnet (d) an adult with an iron
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) False (b) True
3. 3.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) brown (c) white (d) blue
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.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the kind of juice (c) the same paper (d) the iron setting
6. 6.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it can burn skin (d) it is sticky
7. 7.🔍 Which is the odd one out? (a) reading the message (b) putting the iron away (c) dipping the cotton bud (d) writing the message
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) True (b) False
9. 9.True or false: yeast is needed for the secret lemon message. (a) False (b) True
10. 10.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
11. 11.True or false: ironing the paper is a job for an adult. (a) True (b) False
12. 12.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) an adult with an iron (d) a mirror
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
14. 14.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) whoever is fastest (d) only an adult
15. 15.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
16. 16.⚖️ 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
17. 17.🔮 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
18. 18.🛟 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
19. 19.⚖️ 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 keep it the same (c) we change it
20. 20.⚖️ 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 iron setting (c) the same cotton bud (d) how dark the writing is
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we change it (c) we measure it
22. 22.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
23. 23.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
24. 24.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a battery cell (c) a balloon (d) white paper
25. 25.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) letting the paper dry (c) putting the iron away (d) ironing the paper
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) a small bowl (c) an adult with an iron (d) white paper
27. 27.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
28. 28.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
29. 29.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
30. 30.🔍 Which is the odd one out? (a) plugging in the iron (b) writing the message (c) cutting the lemon (d) ironing the paper
31. 31.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a mirror (c) a magnet (d) an adult with an iron
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
33. 33.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a magnet (c) a small bowl (d) a mirror
34. 34.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
35. 35.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
36. 36.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) putting the iron away (c) plugging in the iron (d) cutting the lemon
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we measure it (c) we change it
38. 38.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
40. 40.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) ironing the paper (d) dipping the cotton bud

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