Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 533 · 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) the iron is brown (b) the juice scorches first (c) heat adds colour (d) paper turns lemony
2. 2.🔍 Which is the odd one out? (a) plugging in the iron (b) dipping the cotton bud (c) putting the iron away (d) ironing the paper
3. 3.🍋 Which of these steps is a job for an adult? (a) reading the message (b) plugging in the iron (c) dipping the cotton bud (d) writing the message
4. 4.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) lemon juice (d) turmeric powder
5. 5.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
6. 6.⚖️ 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 kind of juice (c) the iron setting
7. 7.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) reading the message (c) dipping the cotton bud (d) writing the message
8. 8.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) chemical (c) musical (d) magnetic
9. 9.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
10. 10.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
11. 11.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
12. 12.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
13. 13.🔍 Which is the odd one out? (a) reading the message (b) ironing the paper (c) dipping the cotton bud (d) writing the message
14. 14.⚖️ 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 measure it (c) we change it
15. 15.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) yeast (c) turmeric powder (d) a cotton bud
16. 16.⚖️ 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
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) how dark the writing is (c) the same paper (d) the ironing time
18. 18.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
19. 19.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is magnetic (d) it is sticky
20. 20.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
21. 21.⚖️ 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
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we measure it (c) we change it
23. 23.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) green (c) blue (d) white
24. 24.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) a small bowl (c) a cotton bud (d) white paper
25. 25.⚖️ 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) True (b) False
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a balloon (c) a cotton bud (d) an adult with an iron
27. 27.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) a battery cell (d) white paper
28. 28.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) writing turns green (c) the paper floats (d) it gets darker
29. 29.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
30. 30.True or false: letting the paper dry is a job a child can do. (a) False (b) True
31. 31.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) only an adult (d) whoever is fastest
32. 32.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
33. 33.True or false: cutting the lemon is a job for an adult. (a) True (b) False
34. 34.🍋 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) putting the iron away
35. 35.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
36. 36.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) plugging in the iron (d) dipping the cotton bud
37. 37.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) a cotton bud (d) a battery cell
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a magnet (c) a cotton bud (d) a small bowl
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) how dark the writing is (c) the iron setting (d) the kind of juice

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