Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 587 · 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.⚖️ 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
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) the same paper (c) how dark the writing is (d) the iron setting
3. 3.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
4. 4.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) writing the message (d) putting the iron away
5. 5.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) chemical (c) musical (d) magnetic
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.⚖️ 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
8. 8.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) an adult with an iron (c) a cotton bud (d) yeast
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 — plugging in the iron? (a) an adult does it (b) a child can do it
11. 11.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) lemon juice (c) an adult with an iron (d) a battery cell
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) True (b) False
13. 13.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
14. 14.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) whoever is fastest (d) any child
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a balloon (c) white paper (d) an adult with an iron
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a magnet (c) a cotton bud (d) an adult with an iron
17. 17.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) 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 change it (b) we measure it (c) we keep it the same
19. 19.⚖️ 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
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we measure it (c) we keep it the same
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) a magnet (d) a small bowl
22. 22.⚖️ 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
23. 23.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a small bowl (c) a balloon (d) a magnet
24. 24.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
26. 26.True or false: plugging in the iron is a job for an adult. (a) False (b) True
27. 27.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
28. 28.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) the juice scorches first (c) paper turns lemony (d) heat adds colour
29. 29.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) a rainbow (d) almost nothing
30. 30.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the iron setting (c) the same cotton bud (d) the ironing time
32. 32.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
33. 33.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) dry juice is see-through (d) the ink is magnetic
34. 34.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) an adult with an iron (c) a small bowl (d) a cotton bud
36. 36.🧺 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 mirror (d) lemon juice
37. 37.⚖️ 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
38. 38.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
39. 39.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) putting the iron away (c) letting the paper dry (d) writing the message
40. 40.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) cutting the lemon (d) reading the message

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