Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 475 · 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) a cotton bud (b) a small bowl (c) a balloon (d) lemon juice
2. 2.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
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 same paper (b) how dark the writing is (c) the kind of juice (d) the ironing time
4. 4.True or false: putting the iron away is a job for an adult. (a) True (b) False
5. 5.🔍 Which is the odd one out? (a) plugging in the iron (b) reading the message (c) dipping the cotton bud (d) letting the paper dry
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) False (b) True
7. 7.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is magnetic (d) it is cold
8. 8.⚖️ 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
9. 9.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
10. 10.🍋 Which of these steps is a job for an adult? (a) writing the message (b) ironing the paper (c) letting the paper dry (d) dipping the cotton bud
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) lemon juice (c) a small bowl (d) white paper
12. 12.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) brown (c) white (d) green
13. 13.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) reading the message (d) ironing the paper
14. 14.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
15. 15.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) almost nothing (d) a rainbow
16. 16.🔍 Which is the odd one out? (a) plugging in the iron (b) reading the message (c) cutting the lemon (d) putting the iron away
17. 17.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
18. 18.⚖️ 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
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
20. 20.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing stays faint (c) writing turns green (d) it gets darker
21. 21.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
22. 22.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
23. 23.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
24. 24.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
25. 25.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
26. 26.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) the iron is brown (c) heat adds colour (d) paper turns lemony
27. 27.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) lemon juice (d) a magnet
28. 28.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) writing the message (c) plugging in the iron (d) cutting the lemon
29. 29.⚖️ 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) True (b) False
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a magnet (c) a cotton bud (d) white paper
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a cotton bud (c) an adult with an iron (d) yeast
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the iron setting (c) the kind of juice
33. 33.🛟 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
34. 34.⚖️ 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
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) an adult with an iron (c) a cotton bud (d) lemon juice
36. 36.⚖️ 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 same cotton bud (d) how dark the writing is
37. 37.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
38. 38.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) a cotton bud (c) lemon juice (d) a small bowl
39. 39.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
40. 40.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False

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