Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 869 · 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.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) lemon juice (c) a magnet (d) a mirror
2. 2.⚖️ 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
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a mirror (c) a small bowl (d) a cotton bud
4. 4.🔍 Which is the odd one out? (a) writing the message (b) ironing the paper (c) reading the message (d) dipping the cotton bud
5. 5.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
6. 6.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
7. 7.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is sticky (c) it is magnetic (d) it is cold
8. 8.True or false: cutting the lemon is a job for an adult. (a) False (b) True
9. 9.True or false: reading the message is a job a child can do. (a) True (b) False
10. 10.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) chemical (d) musical
11. 11.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the same cotton bud (c) the kind of juice (d) how dark the writing is
13. 13.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) heat adds colour (c) the iron is brown (d) the juice scorches first
14. 14.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
15. 15.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) a small bowl (d) yeast
16. 16.⚖️ 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
17. 17.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
18. 18.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a cotton bud (d) a magnet
20. 20.⚖️ 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
21. 21.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
22. 22.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) reading the message (d) cutting the lemon
23. 23.True or false: cutting the lemon is a job a child can do. (a) True (b) False
24. 24.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) lemon juice (c) white paper (d) a cotton bud
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) how dark the writing is (c) the kind of juice (d) the same paper
26. 26.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
27. 27.True or false: ironing the paper is a job a child can do. (a) True (b) False
28. 28.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
29. 29.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) the paper floats (c) writing turns green (d) it gets darker
30. 30.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) dipping the cotton bud (d) plugging in the iron
31. 31.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a mirror (c) an adult with an iron (d) a battery cell
32. 32.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) lemon juice (d) yeast
34. 34.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we change it (c) we keep it the same
36. 36.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) cutting the lemon (c) writing the message (d) dipping the cotton bud
37. 37.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) whoever is fastest (c) the youngest child (d) any child
38. 38.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
39. 39.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) plugging in the iron (d) reading the message
40. 40.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it

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