Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 583 · 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? Which of these is what we measure? (a) the same paper (b) the kind of juice (c) how dark the writing is (d) the iron setting
2. 2.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) chemical (c) physical (d) musical
3. 3.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
4. 4.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
5. 5.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) heat adds colour (d) the juice scorches first
6. 6.🔍 Which is the odd one out? (a) reading the message (b) cutting the lemon (c) ironing the paper (d) putting the iron away
7. 7.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing stays faint (d) writing turns green
8. 8.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) ironing the paper (d) letting the paper dry
9. 9.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) brown (d) white
10. 10.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
11. 11.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
12. 12.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) whoever is fastest (d) only an adult
13. 13.🔍 Which is the odd one out? (a) letting the paper dry (b) ironing the paper (c) writing the message (d) dipping the cotton bud
14. 14.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) plugging in the iron (d) dipping the cotton bud
15. 15.⚖️ 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 change it (c) we keep it the same
16. 16.⚖️ 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 same cotton bud
17. 17.⚖️ 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 same paper
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) the same paper (c) the same cotton bud (d) the kind of juice
19. 19.🧺 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) lemon juice (d) a battery cell
20. 20.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a battery cell (c) a small bowl (d) lemon juice
21. 21.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) almost nothing (d) dark brown words
22. 22.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) dipping the cotton bud (d) cutting the lemon
23. 23.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
24. 24.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
25. 25.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) writing the message (d) putting the iron away
26. 26.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
27. 27.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) dipping the cotton bud (d) cutting the lemon
28. 28.⚖️ 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
29. 29.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
30. 30.⚖️ 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
31. 31.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it can burn skin (d) it is sticky
32. 32.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) lick your fingers (d) wash your hands
33. 33.True or false: letting the paper dry is a job for an adult. (a) True (b) False
34. 34.True or false: ironing the paper is a job for an adult. (a) True (b) False
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) a balloon (d) white paper
36. 36.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
37. 37.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) it turned into air (d) dry juice is see-through
38. 38.⚖️ 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
39. 39.⚖️ 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 keep it the same (c) we change it
40. 40.True or false: plugging in the iron is a job for an adult. (a) False (b) True

Free science experiments lessons, practice and worksheets at talentjr.in/science-experiments-for-kids