Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 802 · 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 must children keep their fingers away from the iron? (a) it can burn skin (b) it is magnetic (c) it is cold (d) it is sticky
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) True (b) False
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the kind of juice (c) the iron setting (d) how dark the writing is
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we measure it (c) we change it
5. 5.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) dark brown words (c) blue words (d) a rainbow
6. 6.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a balloon (c) white paper (d) a mirror
7. 7.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
8. 8.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) white (d) brown
9. 9.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
10. 10.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a cotton bud (c) yeast (d) a magnet
11. 11.🧺 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) turmeric powder
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) yeast (c) lemon juice (d) a magnet
13. 13.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) cutting the lemon (d) reading the message
14. 14.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
15. 15.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) dipping the cotton bud (d) plugging in the iron
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the iron setting (c) how dark the writing is (d) the kind of juice
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a balloon (d) a cotton bud
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) a cotton bud (c) a small bowl (d) white paper
19. 19.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
20. 20.True or false: reading the message is a job for an adult. (a) False (b) True
21. 21.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
22. 22.🍋 Which of these steps is a job for an adult? (a) writing the message (b) reading the message (c) letting the paper dry (d) ironing the paper
23. 23.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
24. 24.True or false: letting the paper dry is a job for an adult. (a) False (b) True
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) a cotton bud (c) an adult with an iron (d) a small bowl
27. 27.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
28. 28.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) only an adult (d) any child
29. 29.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the ink is magnetic (c) dry juice is see-through (d) the paper ate it
30. 30.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) ironing the paper (d) reading the message
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) a cotton bud (c) lemon juice (d) white paper
32. 32.🔍 Which is the odd one out? (a) plugging in the iron (b) reading the message (c) letting the paper dry (d) writing the message
33. 33.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) an adult with an iron (c) a mirror (d) a magnet
34. 34.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
36. 36.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) plugging in the iron (d) dipping the cotton bud
37. 37.True or false: plugging in the iron is a job a child can do. (a) True (b) False
38. 38.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
39. 39.⚖️ 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) how dark the writing is (c) the kind of juice
40. 40.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing turns green (d) writing stays faint

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